Substituted aluminosilicate compositions and process for preparing

ABSTRACT

This invention relates to molecular sieve compositions and processes for using the molecular sieves. The molecular sieves have a three-dimensional microporous crystalline framework structure of tetrahedral oxide units of AlO 2 , SiO 2 , TiO 2  and/or FeO 2 . These molecular sieves can be prepared by contacting a starting zeolite with a solution or slurry of a fluoro salt of titanium and/or iron under effective process conditions to extract aluminum from the zeolite framework and substitute titanium and/or iron. The molecular sieves can be used as catalysts in hydrocarbon conversion processes and other processes.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a division of application Ser. No. 07/790,312 filedon Dec. 16, 1991, now U.S. Pat. No. 5,176,817, which in turn is adivision of U.S. Ser. No. 559,817 filed Jul. 23, 1990, now U.S. Pat. No.5,098,687, which in turn is a continuation-in-part of U.S. Ser. No.298,629 filed Jan. 18, 1989, now abandoned, which in turn is a divisionof U.S. Ser. No. 604,179 filed Apr. 26, 1984, now U.S. Pat. No.4,892,720, all of which are incorporated by reference.

FIELD OF THE INVENTION

The instant invention relates to novel zeolite compositions, the methodfor their preparation, and to processes employing them. Moreparticularly, it relates to zeolite compositions topologically relatedto prior known zeolites but which are characterized as containingframework atoms of iron and/or titanium, and preferably having a verylow content of defect sites in the structure, as hereinafter disclosed.In general, the preparative process involves contacting the startingzeolite under controlled conditions with an aqueous solution of a fluorosalt of titanium and/or iron, preferably a fluoro salt which does notform insoluble salts with aluminum.

BACKGROUND OF THE INVENTION

The crystal structures of naturally occurring and assynthesized zeoliticaluminosilicates are composed of AlO₄ ⁻ and SiO₄ tetrahedra which arecross-linked by the sharing of oxygen atoms. The electrovalence of eachtetrahedron containing an aluminum atom is balanced by association witha cation. Most commonly, this cation is a metal cation such as Na⁺ or K⁺but organic species such as quaternary ammonium ions are also employedin zeolite synthesis and, in some instances, appear as cations in thesynthesized product zeolite. In general, the metal cations are, to aconsiderable extent at least, replaceable with other cations includingH⁺ and NH₄ ⁺. In many instances, the organic cation species are toolarge to pass through the pore system of the zeolite and, hence, cannotbe directly replaced by ion exchange techniques. Thermal treatments canreduce these organic cations to H⁺ or NH₄ ⁺ cations which can bedirectly ion-exchanged. Thermal treatment of the H⁺ or NH₄ ⁺ cationicforms of the zeolites can result in the substantial removal of thesecations from their normal association with the AlO₄ ⁻ tetrahedra,thereby creating an electrovalent imbalance in the zeolite structurewhich must be accompanied by structural rearrangements to restore theelectrovalent balance. Commonly when AlO₄ ⁻ tetrahedra constitute about40 % or more of the total framework tetrahedra, the necessary structuralrearrangements cannot be accommodated and the crystal structurecollapses. In more siliceous zeolites, the structural integrity issubstantially maintained, but the resulting "decationized" form hascertain significantly different properties from its fully cationizedprecursor.

The relative instability of aluminum in zeolites, particularly in thenon-metallic cationic or the decationized form, is well recognized inthe art. For example, in U.S. Pat. No. 3,640,681, issued to P. E.Pickert on Feb. 3, 1972, there is disclosed a process for extractingframework aluminum from zeolites which involves dehydroxylating apartially cation-deficient form of the zeolite and then contacting itwith acetylacetone or a metal derivative thereof to chelate andsolubilize aluminum atoms. Ethylenediaminetetraacetic acid has beenproposed as an extractant for extracting aluminum from a zeoliteframework in a process which is, in some respects, similar to thePickert process. It is also known that calcining the H⁺ or NH₄ ⁺ cationforms of zeolites such as zeolite Y in an environment of water vapor,either extraneous or derived from dehydroxylation of the zeolite itself,is effective in removing framework aluminum by hydrolysis. Evidence ofthis phenomenon is set forth in U.S. Pat. No. 3,506,400, issued Apr. 14,1970 to P. E. Eberly, Jr. et al.; U.S. Pat. No. 3,493,519, issued May19, 1970 to G. T. Kerr et al.; and U.S. Pat. No. 3,513,108, issued May19, 1970 to G. T. Kerr. In those instances in which the crystalstructure of the product composition is retained after the rigoroushydrothermal treatment involved, infrared analysis indicated thepresence of substantial hydroxyl groups exhibiting a stretchingfrequency in the area of about 3740, 3640 and 3550 cm⁻¹. The infraredanalytical data of U.S. Pat. No. 3,506,400 is especially instructive inthis regard. An explanation of the mechanism of the creation of thesehydroxyl groups is provided by Kerr et al. in U.S. Pat. No. 3,493,519wherein the patentees state that the aluminum atoms in the latticeframework of hydrogen zeolites can react with water resulting in theremoval of aluminum from the lattice in accordance with the followingequation: ##STR1## The aluminum which is removed from its originallattice position is capable of further reaction with cationic hydrogen,according to Kerr et al. to yield aluminum-containing, i.e.,hydroxyloaluminum, cations by the equation: ##STR2## It has beensuggested that stabilization of NH₄ Y occurs through hydrolysis ofsufficient framework aluminum to form stable clusters of thesehydroxoaluminum cations within the sodalite cages, thereby holding thezeolite structure together while the framework anneals itself throughthe migration of some of the framework silicon atoms.

It is alleged in U.S. Pat. No. 3,594,331, issued Jul. 20, 1971 to C. H.Elliott, that fluoride ions in aqueous media, particularly underconditions in which the pH is less than about 7, are quite effective inextracting framework aluminum from zeolite lattices, and, in fact, whenthe fluoride concentration exceeds about 15 grams active fluoride per10,000 grams of zeolite, destruction of the crystal lattice by thedirect attack on the framework silicon as well as on the frameworkaluminum can result. A fluorid treatment of this type using from 2 to 22grams of available fluoride per 10,000 grams of zeolite (anhydrous) inwhich the fluorine is provided by ammonium fluorosilicate is alsodescribed therein. The treatment is carried out for the purpose ofimproving the thermal stability of the zeolite. It is theorized by thepatentee that the fluoride in some manner becomes attached to theconstructional alkali metal oxide, thereby reducing the fluxing actionof the basic structural Na₂ O which would otherwise result in thecollapse of the crystal structure. Such treatment within the constraintsof the patent disclosure has no effect on either the overall siliconcontent of the zeolite product or the silicon content of a unit cell ofthe zeolite.

Since stability is quite obviously, in part at least, a function of theA₂ O₃ content of the zeolite framework, it would appear to beadvantageous to obtain zeolites having lower proportions of Al₂ O₃ whileavoiding the structural changes inherent in framework aluminumextraction. Despite considerable effort in this regard, however, onlyvery modest success has been achieved, and this has applied to a fewindividual species only.

A process for increasing the SiO₂ /Al₂ O₃ ratio in zeolites is disclosedin U.S. Pat. No. 4,503,023. The process disclosed therein comprisesinserting silicon atoms as SiO₄ tetrahedra into the crystal lattice ofan aluminosilicate having a SiO₂ /Al₂ O₃ molar ratio of at least 3 andpore diameters of at least 3 Angstroms with a fluorosilicate salt in anamount of at least 0.0075 moles per 100 grams of the zeoliticaluminosilicate on an anhydrous basis, said fluorosilicate salt being inthe form of an aqueous solution having a pH value within the range of 3to about 7 and brought into contact with the zeolitic aluminosilicate ata rate sufficiently slow to preserve at least 60 percent of thecrystallinity of the starting zeolitic aluminosilicate.

The difficulty which is met in preparing titanium-containing molecularsieve compositions is further demonstrated by the failure of EuropeanPatent Application No. 82109451.3 (Publication No. 77,522 published Apr.27, 1983) entitled "Titanium-Containing Zeolites and Method for TheirProduction as Well as Use of Said Zeolites", to actually preparetitanium-containing molecular sieve compositions. Although theapplicants claim the preparation of titano-aluminosilicates having thepentasil structure, it is evident from an analysis of the products ofthe examples that titanium was not present in the form of a frameworktetrahedral oxide. The products of the examples of European patentApplication No. 82109451.3 will be discussed in detail in comparativeexamples hereinafter.

Another reference which deals with titano-aluminosilicates is U.S. Pat.No. 4,410,501 to Taramasso. This reference primarily deals with thepreparation of titanium silicates and only in passing does it mention atitanium/aluminum/silicon composition. The patentee presents one example(Example 8) in which it is stated that the addition of aluminum changedthe characteristics of the titanium silicate. As will be shown in detailhereinafter, this change in property is owing to the fact that whatTaramasso made was ZSM-5 and not a titano-aluminosilicate. In factTaramasso does not provide any evidence at all to show that titanium wasincorporated into the aluminosilicate lattice.

DESCRIPTION OF THE FIGURE

FIG. 1 is a ternary diagram wherein parameters relating to the instantcompositions are set forth as mole fractions.

SUMMARY OF THE INVENTION

This invention relates to molecular sieves and processes using thesemolecular sieves. Accordingly, one embodiment of the invention is amolecular sieve composition having a three-dimensional microporousframework structure of AlO₂, SiO₂, TiO₂ and/or FeO₂ tetrahedral oxideunits and having a unit empirical formula on an anhydrous basis of:

    (Σ.sub.w Al.sub.x Si.sub.y)O.sub.2

where "Σ" is at least titanium and/or iron; and "w", "x" and "y"represent one of the mole fractions of "Σ", aluminum and silicon,respectively, present as framework tetrahedral oxide units, said molefractions being such that they are within the compositional area definedby points A, B and C of FIG. 1.

A particular embodiment of the invention is where Σ is titanium.

Another embodiment of this invention is a process for converting ahydrocarbon feed to a hydrocarbon converted product, which comprisescontacting said hydrocarbon feed under hydrocarbon converting conditionswith a molecular sieve as described above.

Yet another embodiment of the invention is a method of separating amixture of molecular species on the basis of molecular size (kineticdiameters) or on the degree of polarity of the species comprisingcontacting the molecular species with a molecular sieve as describedabove.

Other objects and embodiments of this invention will become apparent inthe following detailed description.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to new molecular sieve compositions and tothe processes for their use. The molecular sieves of the instantinvention have three-dimensional microporous crystal frameworkstructures of "ΣO₂ ", AlO₂ and SiO₂ tetrahedral units which have a unitempirical formula on an anhydrous basis of:

    (Σ.sub.w Al.sub.x Si.sub.y)O.sub.2                   (1)

wherein "Σ" represents at least one of titanium and/or iron; and "w","x" and "y" represent the mole fractions of "Σ", aluminum and silicon,respectively, present as tetrahedral oxides, said mole fractions beingsuch that they are within the trigonal compositional area defined bypoints A, B and C and representing the following values for "w", "x",and "y":

    ______________________________________                                               Mole Fraction                                                          Point    w              x      y                                              ______________________________________                                        A        0.49           0.01   0.50                                           B        0.01           0.49   0.50                                           C        0.01           0.01   0.98                                           ______________________________________                                    

The term "unit empirical formula" is used herein according to its commonmeaning to designate the simplest formula which gives the relativenumber of moles of titanium and/or iron, aluminum and silicon which form"ΣO₂ ", AlO₂, and SiO₂ tetrahedral units within the molecular sieve. Theunit empirical formula is given in terms of titanium and/or iron,aluminum and silicon as shown in Formula (1), above, and does notinclude other compounds, cations or anions which may be present as aresult of the preparation or the existence of other impurities ormaterials in the bulk composition not containing the aforementionedtetrahedral units.

The instant process generally comprises a method for removing frameworkaluminum from zeolites having SiO₂ /AlO₃ mole ratios of about 3 orgreater and substituting therefor one or more elements selected from thegroup consisting of titanium and iron. The resulting molecular sievescontain titanium and/or iron and have crystal structures similar to thatof the initial zeolite.

The process of the invention comprises contacting a crystalline zeolitehaving pore diameters of at least about 3 Angstroms and having a molarSiO₂ /AlO₃ ratio of at least 3, with an effective amount of fluoro saltof titanium and/or iron, preferably in an amount of at least 0.001 molesper 100 grams of zeolite starting material, said fluoro salt being inthe form of an aqueous solution or slurry and brought into contact withthe zeolite either incrementally or continuously at a slow rate(optionally in the presence of a buffer) whereby framework aluminumatoms of the zeolite are removed and replaced by titanium and/or ironatoms. It is desirable that the process be carried out such that atleast 60, preferably at least 80, and more preferably at least 90percent of the crystal structure of the starting zeolite is retained andthat the Defect Structure Factor (hereinafter defined) is increased byless than 0.15, and preferably by less than 0.10.

Crystalline zeolite starting materials suitable for the practice of thepresent invention can be any of the well known naturally occurring orsynthetically produced zeolite species which have pores large enough topermit the passage of water, titanium and/or iron fluoro salts andreaction products through their internal cavity system. These materialscan be represented, in terms of molar ratios of oxides, as

    M.sub.2/n O: Al.sub.2 O.sub.3 : x SiO.sub.2 : y H.sub.2 O

wherein "M" is a cation having the valence "n", "x" is a value of atleast about 3 and "y" has a value of from zero to about 9 depending uponthe degree of hydration and the capacity of the particular zeolite tohold absorbed water. Alternatively, the framework composition of thenaturally occurring or synthetic zeolite starting material can beexpressed in terms of the mole fraction of framework tetrahedra, TO₂,as:

    (Al.sub.a Si.sub.b)O.sub.2                                 (2)

wherein "a" is the fraction of framework tetrahedral sites occupied byaluminum atoms and "b" is the fraction of framework tetrahedral sitesoccupied by silicon atoms. Should the framework of the starting materialcontain atoms in addition to silicon and aluminum, these materials maybe similarly expressed in terms of their "TO₂ " formula in terms oftheir fractional occupation of the framework of the starting material.The algebraic sum of all of the subscripts within the brackets is equalto 1. In the above example, a+b=1.

Representative of the crystalline aluminosilicate zeolite molecularsieves which may be employed in the instant process include, but are notlimited to erionite, mordenite, clinoptilolite, zeolite Y, zeolite L,zeolite LZ-105, zeolite omega, zeolite beta, zeolite TMA offretite,zeolite ZSM-5, zeolite ZSM-34, zeolite ZSM-35, and zeolite LZ-202. Bothnaturally occurring and synthetically prepared zeolite molecular sievescan be used. Zeolite Y is disclosed in U.S. Pat. No. 3,130,007; zeoliteL is disclosed in U.S. Pat. No. 3,216,789; zeolite LZ-105 is disclosedin U.S. Pat. No. 4,257,885; zeolite omega is disclosed in U.S. Pat. No.4,241,036; zeolite beta is disclosed in U.S. Pat. No. 3,308,069; zeoliteZSM-5 is disclosed in U.S. Pat. No. 3,702,886; and ZSM-34 is disclosedin U.S. Pat. No. 4,086,186; and zeolite ZSM-35 is disclosed in U.S. Pat.No. 3,992,466.

For reasons more fully explained hereinafter, the starting zeoliteshould be able to withstand the initial loss of framework aluminum atomsto at least a modest degree without collapse of the crystal structureunless the process is to be carried out at a very slow rate. In general,the ability to withstand aluminum extraction and maintain a high levelof crystallinity is directly proportional to the initial SiO₂ /Al₂ O₃molar ratio of the zeolite. Accordingly, it is preferred that the valuefor "x" in the formula above, be at least about 3. Also, it is preferredthat at least about 50, and more preferably at least 95% of the AlO₄tetrahedra of the naturally occurring or as-synthesized zeolite arepresent in the starting zeolite. Most advantageously the startingzeolite contains as many as possible of its original AlO₄ tetrahedra,i.e., has not been subjected to any post-formation treatment whicheither extensively removes aluminum atoms from their original frameworksites or converts them from the normal conditions of 4-fold coordinationwith oxygen.

The cation population of the starting zeolite is not a critical factorinsofar as substitution of titanium and/or iron for framework aluminumis concerned, but since the substitution mechanism may involve the insitu formation of salts of at least some of the zeolitic cations, it isadvantageous that these salts be water-soluble to a substantial degreeto facilitate their removal from the molecular sieve product. It isfound that ammonium cations form the most soluble salts in this regardand it is accordingly preferred that at least 50 percent, mostpreferably 85 or more percent, of the zeolite cations be ammonium orhydronium cations. Sodium and potassium, two of the most common cationspresent in zeolites, are found to form Na₃ AlF₆ and K₃ AlF₆respectively, both of which are only very sparingly soluble in eitherhot or cold water. When these compounds are formed as precipitateswithin the structural cavities of the zeolite, they are quite difficultto remove by water washing. Their removal, moreover, is important ifthermal stability of the molecular sieve product is desired sincesubstantial amounts of fluoride can cause crystal collapse attemperatures as low as 500° C.

For purposes of simplifying the description of the products of the aboveprocess, as above defined, the framework composition of the zeolitestarting material and the products of the instant process are expressedin terms of mole fractions of framework tetrahedra, i.e., the "TO₂ ".The starting zeolite may be expressed as:

    (Al.sub.a Si.sub.b [ ].sub.z)O.sub.2

where "a" is the mole fraction of aluminum tetrahedra in the framework;"b" is the mole fraction of silicon tetrahedra in the framework; "[ ]"denotes defect sites in the framework; and "z" is the mole fraction ofdefect sites in the zeolite framework. In many cases, the "z" value forthe starting zeolite is zero and the defect sites are simply eliminatedfrom the expression. Numerically the sum of the values a+b+z=1.

The molecular sieves products of the instant process, expressed in termsof the mole fractions of framework tetrahedra (TO₂) will have the form:

    [Al.sub.(a-N) Si.sub.b Σ.sub.c [ ].sub.z ]O.sub.2

wherein "(a-N)" is the mole fraction of aluminum tetrahedra in themolecular sieve, "N" is defined as the mole fraction of aluminumtetrahedra removed from the framework during the treatment; "a" is themole fraction of aluminum tetrahedra present in the framework of thestarting zeolite; "b" is the mole fraction of silicon tetrahedra presentin the framework of the starting zeolite; "z" is the mole fraction ofdefect sites in the framework and ranges from greater than zero to about0.2; the Greek letter sigma, "Σ" denotes at least one of titanium andiron; and "c" is the mole fraction of titanium and/or iron tetrahedraresulting from the fluoro salt treatment of the instant process andvaries from 0.01 to 0.49. Theoretically, there should be no change inthe silicon content and therefore "c" should equal (N-Δz) where "Δz" isthe net change in the mole fraction of defect sites in the zeoliteframework resulting from the treatment, Δz=z (product zeolite) -z(starting zeolite) and is generally less than about 0.10. The term"Defect Structure Factor" for any given zeolite is equivalent to the "z"value of that particular zeolite. The net change in Defect StructureFactors between the starting zeolite and the product zeolite isequivalent to "Δz". Numerically, the sum of the values:

    (a-N)+b+c+z=1; and

    (a-N)+b+(N-Δz)+z=1

The titanium and iron-containing molecular sieve compositions preparedby the instant process have framework aluminum removed from the startingzeolite with substitution therefor by titanium and/or iron. The instantprocess generally comprises contacting a crystalline zeolite having apore diameter of at least about 3 Angstroms and having a molar SiO₂ /Al₂O₃ ratio of at least 3, with an effective amount of a fluoro salt oftitanium and/or iron, preferably an amount of at least 0.001 moles offluoro salt per 100 grams of zeolite starting material, said fluoro saltbeing in the form of a solution or slurry, preferably aqueous and/oralcohols, at an effective pH where the pH value is generally greaterthan one (1), more preferably greater than 3 and most preferably in therange of about 3 to about 7. The fluoro salt solution or slurry isbrought into contact with the zeolite either incrementally orcontinuously at a slow rate whereby framework aluminum atoms of thezeolite are removed and replaced by titanium and/or iron atoms from thefluoro salt. The fluoro salt is preferably provided as an aqueoussolution or slurry but it is believed that solutions or slurriesemploying alcohols and other organic solvents may be employed.

The process generally comprises:

(a) contacting at effective process conditions a zeolite with aneffective amount of a fluoro salt of titanium and/or iron; and

(b) isolating the titanium and/or iron-containing molecular sieveproduct from the reaction mixture.

The fluoro salt is in the form of a solution or slurry, preferablyaqueous, and is brought into contact with the zeolite eitherincrementally or continuously at an effective rate such that a portionof the framework aluminum atoms are removed and replaced by titaniumand/or iron atoms at a rate which preferably retains at least 80 percentand more preferably at least 90 percent of the crystal structure of thestarting zeolite.

For reasons more fully explained hereinafter, the starting zeoliteshould be able to withstand the initial loss of framework aluminum atomsto at least a modest degree without collapse of the crystal structureunless the process is to be carried out at a very slow pace, or theprocess is to be buffered as hereinbefore discussed. Accordingly, theSiO₂ /Al₂ O₃ ratio in the initial Y zeolite starting material ispreferably at least about 3.0. It is preferred that at least about 50%,and more preferably at least 95%, of the Al₄ ⁻ tetrahedra of thenaturally occurring or as-synthesized synthetic zeolite are present inthe starting zeolite, i.e., the starting zeolite has not been subjectedto any post-formation treatment which either extensively removesaluminum atoms from their original framework sites or converts them fromthe normal conditions of 4-fold coordination with oxygen.

The fluoro salt used as the aluminum extractant and also as the sourceof titanium and/or iron, which is inserted into the zeolite structure inplace of the extracted aluminum, can be any of the fluoro salts havingthe general formula:

    (A).sub.2/b ΣF.sub.6 ; (A).sub.2/b ΣF.sub.5 ; or (A).sub.2/b ΣF.sub.4

wherein "Σ" is titanium and/or iron and "A" is a metallic ornon-metallic cation, having the valence "b". Cations represented by "A"include alkylammonium, NH₄, H⁺, Mg⁺⁺, Li⁺, Na⁺, K⁺, Ba⁺⁺, Cd⁺⁺, Cu⁺,Cu⁺⁺, Ca⁺⁺, Cs⁺, Fe⁺⁺, Co⁺⁺, Pb⁺⁺, Mn⁺⁺, Rb⁺, Ag⁺, Sr⁺, Tl⁺ and Zn⁺⁺.The ammonium cation form of the fluoro salt is generally preferredbecause of its solubility in water and also because the ammonium cationsform water soluble by-product salts upon reaction with the zeolite,namely

    (NH.sub.4).sub.3 AlF.sub.6 and/or (NH.sub.4).sub.2 AlF.sub.5.

The manner in which the fluoro salt of titanium and/or iron and thestarting zeolite are brought into contact and the overall process ofsubstituting titanium and/or iron for aluminum in the zeolite frameworkis believed to be a two-step process in which the aluminum extractionstep tends to, unless controlled, proceed very rapidly while theinsertion of titanium and/or iron is generally relatively slow. Ifdealumination becomes too extensive without the substitution of titaniumand/or iron the crystal structure becomes seriously degraded andultimately collapses. While not wishing to be bound by any particulartheory, it appears that fluoride ion acts as the agent for extraction offramework aluminum in accordance with the equation: ##STR3## It isimportant, therefore, that the initial dealumination step be inhibitedand the step involving insertion of titanium and/or iron be promoted toachieve the desired molecular sieve products. It is found that thevarious zeolites have varying degrees of resistance toward degradationas a consequence of framework aluminum extraction without substitutionof titanium and/or iron into the framework. The rate of aluminumextraction generally decreases as the pH of the fluoro salt solution incontact with the zeolite is increased below about one (1) (andaccordingly the pH is preferably within the range of 3 to 7) and as theconcentration of the fluoro salt of titanium and/or iron in the reactionsystem is decreased. Also, increasing the reaction temperature tends toincrease the rate of substitution of titanium and/or iron. Whether it isnecessary or desirable to buffer the reaction system or select aparticular fluoro salt concentration to control the pH it is readilydetermined for each zeolite species by routine observation andevaluation. The question of whether the reaction system mayadvantageously be buffered will, in large part, depend on the selectionof the particular starting zeolite, since zeolites have varyingtolerances to acid and base media. For example, some zeolites canwithstand very low pH conditions and a high level of dealuminationwithout collapse of the crystal structure. When it is advantageous tobuffer the reaction mixture in a particular pH range, the reactionmixture may be buffered in a manner as generally heretofore employed inthe art. The use of buffering salts, such as ammonium acetate, or use ofan inert solid to react with excess acid or base, e.g., clays oraluminas, may be generally employed to buffer the pH of the reactionmixture.

Theoretically, there is no lower limit for the concentration of fluorosalt of titanium and/or iron in the aqueous solution or slurry employed,provided of course the effective pH (the "effective pH" is a pH suchthat under effective process conditions a monomeric form of titanium ispresent in the reaction system) of the solution or slurry is high enoughto avoid undue destructive acidic attack on the particular zeolitestructure apart from the intended reaction with an effective amount ofthe fluoro salt, i.e., that amount which provides sufficient fluorideand amount of titanium and/or iron for the process and desired amount oftitanium and/or iron in the final molecular sieve product. A slow rateof addition of the fluoro salt generally provides adequate time for theinsertion of titanium and/or iron as a framework substitute forextracted aluminum before excessive aluminum extraction occurs withconsequent collapse of the crystal structure. Practical commercialconsiderations, however, may require that the reaction proceed asrapidly as possible, and accordingly the conditions of reactiontemperature and reagent concentrations will necessarily be optimizedwith respect to each zeolite starting material and with respect tocommercial operation. In general, it is believed that the more highlysiliceous the zeolite, the higher the permissible reaction temperatureand the lower the pH conditions which may be employed in the instantprocess. In general, the preferred effective reaction temperature iswithin the range between about 10° C. and about 99° C., preferablybetween about 20° C. and 95° C., but temperatures of 125° C. or higherand as low as 0° C. are believed employable in some instances with somezeolite starting materials and with fluoro salts in a form other thanaqueous solutions or slurries. At pH values below about 3 crystaldegradation of many zeolites is found to be unduly severe, whereas at pHvalues higher than 7, insertion of the titanium and/or iron may be slowfrom a practical standpoint as a result of the solubility of titaniumand iron at these pHs and as a result of certain polymerizationreactions. The maximum concentration of fluoro salt in the aqueoussolution employed is, of course, interrelated to the temperature and pHfactors and also with the time of contact between the zeolite and thesolution and the relative proportions of zeolite and fluoro salt.Solutions having fluoro salt concentrations of between about 10⁻³ molesper liter of solution and up to saturation of the solution can beemployed, but is preferred that concentrations in the range of betweenabout 0.5 and about 1.0 moles per liter of solution be used. Inaddition, as hereinbefore discussed, slurries of the fluoro salts oftitanium and/or iron may be employed. The aforementioned concentrationvalues are with respect to true solutions, and are not intended to applyto the total fluoro salts in solution or in slurries of the salts inwater. Even very slightly soluble fluoro salts can be slurried in waterand used as a reagent--the undissolved solids being readily available toreplace dissolved molecular species consumed in reaction with thezeolite. As stated hereinabove, the amount of dissolved fluoro saltsemployed with respect to the particular zeolite being treated willdepend to some extent upon the physical and chemical properties of theindividual zeolites and other effective process conditions. However, theminimum value for the amount of fluoro salt to be added is preferably atleast equivalent to the minimum mole fraction of aluminum to be removedfrom the zeolite.

In specifying the proportions of the zeolite starting material oradsorption properties of the zeolite product and the like herein, the"anhydrous state" of the zeolite will be intended unless otherwisestated. The term "anhydrous state" is employed herein to refer to amaterial substantially devoid of both physically adsorbed and chemicallyadsorbed water. In general, a zeolite may be prepared in the anhydrousstate by heating the zeolite in dry air at about 450° C. for about 4hours.

It is apparent from the foregoing that, with respect to effectiveprocess conditions, it is desirable that the integrity of the zeolitecrystal structure be substantially maintained throughout the process andthat, in addition to having titanium and/or iron atoms inserted into thelattice, the zeolite retains at least 60 percent, preferably at least 80and more preferably at least 90 percent of its original crystallinity. Aconvenient technique for assessing the crystallinity of the productsrelative to the crystallinity of the starting material is the comparisonof the relative intensities of the d-spacings of their respective X-raypowder diffraction patterns. The sum of the peak heights, in terms ofarbitrary units above background, of the starting material is used asthe standard and is compared with the corresponding peak heights of theproducts. When, for example, the numerical sum of the peak heights ofthe molecular sieve product is 85 percent of the value of the sum of thepeak heights of the starting zeolite, then 85 percent of thecrystallinity has been retained. In practice it is common to utilizeonly a portion of the d-spacing peaks for this purpose as, for example,five of the six strongest d-spacings. In zeolite Y these d-spacingscorrespond to the Miller Indices 331, 440, 533, 642 and 555. Otherindicia of the crystallinity retained by the zeolite product are thedegree of retention of surface area and the degree of retention of theadsorption capacity. Surface areas can be determined by the well-knownBrunauer-Emmett-Teller method (B-E-T). J. Am. Chem. Soc. 60 309 (1938)using nitrogen as the adsorbate. In determining the adsorption capacity,the capacity for oxygen at -183° C. at 100 Torr is preferred.

All available evidence, to date, indicates that the above describedprocess of this invention is unique in being able to produce zeolitesessentially free of defect structure and having titanium and/or ironinserted into the framework by a secondary synthesis process.

In untreated, i.e., naturally occurring or as-synthesized zeolites theoriginal tetrahedral structure is conventionally represented as ##STR4##After treatment with a complexing agent such asethylene-diaminetetraacetic acid (H₄ ETDA) in which a stoichiometricreaction occurs whereby framework aluminum atoms along with anassociated cation such as sodium is removed as NaAlEDTA , it ispostulated that the tetrahedral aluminum is replaced by four protonswhich form a hydroxyl "nest", as follows: ##STR5## The infrared spectrumof the aluminum depleted zeolite will show a broad nondescriptabsorption band beginning at about 3750 cm⁻¹ and extending to about 3000cm⁻¹. The size of this absorption band or envelope increases withincreasing aluminum depletion of the zeolite. The reason that theabsorption band is so broad and without any specific absorptionfrequency is that the hydroxyl groups in the vacant sites in theframework are coordinated in such a way that they interact with eachother (hydrogen bonding). The hydroxyl groups of adsorbed watermolecules are also hydrogen-bonded and produce a similar broadabsorption band as do the "nest" hydroxyls. Also, certain other zeolitichydroxyl groups, exhibiting specific characteristic absorptionfrequencies within the range of interest, will, if present, causeinfrared absorption bands in these regions which are superimposed on theband attributable to the "nest" hydroxyl groups. These specifichydroxyls are created by the decomposition of ammonium cations ororganic cations present in the zeolite.

It is, however, possible to treat zeolites, prior to subjecting them toinfrared analysis, to avoid the presence of the interfering hydroxylgroups and thus be able to observe the absorption attributable to the"nest" hydroxyls only. The hydroxyls belonging to adsorbed water areavoided by subjecting the hydrated zeolite sample to vacuum activationat a moderate temperature of about 200° C. for about 1 hour. Thistreatment permits desorption and substantially complete removal of theadsorbed water. Complete removal of adsorbed water can be ascertained bynoting when the infrared absorption band at about 1640 cm⁻¹, the bendingfrequency of water molecules, has been removed from the spectrum.

The decomposable ammonium cations can be removed, at least in largepart, by ion-exchange and replaced with metal cations, preferably bysubjecting the ammonium form of the zeolite to a mild exchange treatmentwith an aqueous NaCl solution. The OH absorption bands produced by thethermal decomposition of ammonium cations are thereby avoided.Accordingly, the absorption band over the range of 3745 cm⁻¹ to about3000 cm⁻¹ for a zeolite so treated is almost entirely attributable tohydroxyl groups associated with defect structure and the absoluteabsorbance of this band can be a measure of the degree of aluminumdepletion.

It is found, however, that the ion-exchange treatment, which mustnecessarily be exhaustive even though mild, required considerable time.Also the combination of the ion-exchange and the vacuum calcination toremove adsorbed water does not remove every possible hydroxyl other thandefect hydroxyls which can exhibit absorption in the 3745 cm⁻¹ to 3000cm⁻¹ range. For instance, a rather sharp band at 3745 cm⁻¹ has beenattributed to the Si--OH groups situated in the terminal latticepositions of the zeolite crystals and to amorphous (non-zeolitic) silicafrom which physically adsorbed water has been removed. For these reasonswe prefer to use a somewhat different criterion to measure the degree ofdefect structure in the zeolite products of this invention.

In the absence of hydrogen-bonded hydroxyl groups contributed byphysically adsorbed water, the absorption frequency least affected byabsorption due to hydroxyl groups other than those associated withframework vacancies or defect sites is at 3710±5 cm⁻¹. Thus, therelative number of defect sites remaining in a zeolite product of thisinvention can be gauged by first removing any adsorbed water from thezeolite, determining the value of the absolute absorbance in itsinfrared spectrum at a frequency of 3710 cm⁻¹, and comparing that valuewith the corresponding value obtained from the spectrum of a zeolitehaving a known quantity of defect structure. The following specificprocedure has been arbitrarily selected and used to measure the amountof defect structure in the products prepared in the examples appearinghereinafter. Using the data obtained from this procedure, it ispossible, using simple mathematical calculation, to obtain a single andreproducible value hereinafter referred to as the "Defect StructureFactor", denoted hereinafter by the symbol "z", which can be used incomparing and distinguishing the present novel zeolite compositions fromtheir non-titanium and/or iron containing counterparts.

DEFECT STRUCTURE FACTOR "Z" (A) Defect Structure Zeolite Standard

Standards with known amounts of defect structure can be prepared bytreating a crystalline zeolite of the same species as the product samplewith ethylene-diaminetetraacetic acid by the standard procedure of Kerras described in U.S. Pat. No. 3,442,795. In order to prepare thestandard it is important that the starting zeolite be well crystallized,substantially pure and free from defect structure. The first two ofthese properties are readily determined by conventional X-ray analysisand the third by infrared analysis using the procedure set forth in part(B) hereof. The product of the aluminum extraction should also be wellcrystallized and substantially free from impurities. The amount ofaluminum depletion, i.e., the mole fraction of tetrahedral defectstructure of the standard samples can be ascertained by conventionalchemical analytical procedure. The molar SiO₂ /Al₂ O₃ ratio of thestarting zeolite used to prepare the standard sample in any given caseis not narrowly critical, but is preferably within about 10% of themolar SiO₂ /Al₂ O₃ ratio of the same zeolite species used as thestarting material in the practice of the process of the presentinvention.

(B) Infrared Spectrum of Product Samples and Defect Structure ZeoliteStandard

Fifteen milligrams of the hydrated zeolite to be analyzed are pressedinto a 13 mm. diameter self-supporting wafer in a KBr die under 5000lbs. pressure. The wafer is then heated at 200° C. for 1 hour at apressure of not greater than 1×10⁻⁴ mm. Hg to remove all observabletraces of physically adsorbed water from the zeolite. This condition ofthe zeolite is evidenced by the total absence of an infrared absorptionat 1640 cm⁻¹. Thereafter, and without contact with adsorbablesubstances, particularly water vapor, the infrared spectrum of the waferis obtained on an interferometer system at 4 cm⁻¹ resolution over thefrequency range of at least 3745 to 3000 cm⁻¹. Both the product sampleand the standard sample are analyzed using the same interferometersystem to avoid discrepancies in the analysis due to differentapparatus. The spectrum, normally obtained in the transmission mode ofoperation is mathematically converted to and plotted as wave number vs.absorbance.

(C) Determination of the Defect Structure Factor

The defect structure factor (z) is calculated by substituting theappropriate data into the following formula: ##EQU1## wherein AA (ps) isthe infrared absolute absorbance measured above the estimated backgroundof the product sample at 3710 cm⁻¹ ; AA (std) is the absolute absorbancemeasured above the background of the standard at 3710 cm⁻¹ and the molefraction of defects in the standard are determined in accordance withpart (A) above.

Once the defect structure, z, is known, it is possible to determine fromthe wet chemical analysis of the product sample for SiO₂, Al₂ O₃,titanium and/or iron and the cation content as M_(2/n) O whethertitanium and/or iron has been substituted for aluminum in the zeolite asa result of the treatment and also the efficiency of the substitution oftitanium and/or iron.

The essential X-ray powder diffraction patterns appearing in thisspecification and referred to in the appended claims are obtained usingeither: (1) standard X-ray powder diffraction techniques; or (2)computer based techniques using copper K-alpha radiation and usingSiemens D-500 X-ray powder diffractometers with Siemens Type K-805 X-raysources, available from Siemens Corporation, Cherry Hill, N.J., withappropriate computer interface. When employing the standard X-raytechnique the radiation source is a high-intensity, copper target, x-raytube operated at 50 Kv and 40 ma. The diffraction pattern from thecopper K alpha radiation and graphite monochromator is suitably recordedby an X-ray spectrometer scintillation counter, pulse-height analyzerand strip-chart recorder. Flat compressed powder samples are scanned at2θ (2 theta) per minute, using a 2 second time constant. Interplanarspacings (d) are obtained from the position of the diffraction peaksexpressed as 2 theta, where 2 theta is the Bragg angle as observed onthe strip chart. Intensities are determined from the heights ofdiffraction peaks after subtracting background.

In determining the cation equivalency, i.e. the molar ratio M_(2/n)O/Al₂ O₃ in each zeolite product, it is advantageous to perform theroutine chemical analysis on a form of the zeolite in which "M" is amonovalent cation other than hydrogen. This avoids the uncertainty whichcan arise in the case of divalent or polyvalent metal zeolite cations asto whether the full valence of the cation is employed in balancing thenet negative charge associated with each AlO₄ ⁻ tetrahedron or whethersome of the positive valence of the cation is used in bonding with OH⁻or H₃ O⁺ ions.

The following examples are provided to illustrate the invention and arenot intended to be limiting thereof:

EXAMPLE 1

(1) Ten grams (gm) of an ammonium-exchanged zeolite Y containing 43.5millimoles of aluminum, as Al₂ O₃, were slurried in 100 milliliters (ml)of an aqueous 3.5 molar solution of ammonium acetate at a temperature of75° C. Because of the limited solubility of (NH₄)₂ TiF₆, the fluoro saltwas added to the slurry as crystals. The weight of added (NH₄)₂ TiF₆ was4.78 grams. The amount of fluoro salt is an amount sufficient to replace55% of the aluminum of the zeolite with titanium. The resulting reactionmixture was then digested for 17 hours at 75° C. The reaction mixturewas then filtered and washed with warm distilled water until qualitativetesting of the wash water was negative for both aluminum and fluorideions. The chemical analyses for the starting zeolite Y and the molecularsieve product prepared therefrom (hereinafter referred to as "LZ-225")are set forth in Table 1:

                  TABLE 1                                                         ______________________________________                                                         Starting                                                                             LZ-225                                                                 Zeolite Y                                                                            Product                                               ______________________________________                                        Na.sub.2 O, weight percent                                                                       2.53     1.56                                              (NH.sub.4).sub.2 O, weight percent                                                               9.51     4.50                                              TiO.sub.2, weight percent                                                                        --       16.23                                             Al.sub.2 O.sub.3, weight percent                                                                 22.18    10.00                                             SiO.sub.2, weight percent                                                                        64.38    63.75                                             F.sub.2, weight percent                                                                          --       0.10                                              SiO.sub.2 /Al.sub.2 O.sub.3                                                                      4.93     10.82                                             Na.sup.+ /Al       0.19     0.26                                              NH.sub.4.sup.+ /Al 0.84     0.80                                              Cation Equivalent, M.sup.+ /Al                                                                   1.03     1.06                                              Si/(Al.sub.2 + Ti.sub.2)                                                                         4.93     5.31                                              ______________________________________                                    

A comparison of the properties of the LZ-225 product with the startingZeolite Y is shown in Table 2.

                  TABLE 2                                                         ______________________________________                                                         Starting                                                                             LZ-225                                                                 Zeolite Y                                                                            Product                                               ______________________________________                                        X-Ray Crystallinity,                                                          % by Peak Intensity:                                                                             100      48                                                Unit Cell, a.sub.o in Å:                                                                     24.712   24.590                                            Crystal Collapse Temp.                                                                           890      962                                               °C. (DTA):                                                             Framework Infrared:                                                           Asymmetric Stretch, cm.sup.-1 :                                                                  1015     1031                                              Symmetric Stretch, cm.sup.-1 :                                                                   789      794                                               Hydroxyl Infrared:                                                            Absolute Absorbance                                                                              0.020    0.194                                             at 3710 cm.sup.-1 :                                                           Defect Structure   0.009    0.082                                             Factor, z:                                                                    McBain Adsorption:                                                            Wt. % O.sub.2, 100 torr.                                                                         35.2     28.4                                              -183° C.:                                                              Wt. % H.sub.2 O, 4.6 torr.                                                                       32.1     27.6                                              25° C.:                                                                ______________________________________                                    

(2) The framework mole fractions of tetrahedra are set forth below forthe starting Zeolite Y and the LZ-225 molecular sieve product and were:

(a) Mole fraction of Oxides (TO₂): Starting Zeolite Y: (Al₀.286 Si₀.705[ ]₀.009)O₂ LZ-225 Product: (Al₀.123 Si₀.667 Ti₀.128 [ ]₀.082)O₂

(b) Mole fraction of aluminum removed, N:0.163

(c) Percent aluminum removed, N/A×100:57

(d) Change in Defect Structure Factor, Δz:0.073

(e) Moles of titanium substituted per mole of aluminum removed: 0.79

(3) The molecular sieves denominated herein as "LZ-225" have thecharacteristic crystal structure of zeolite Y as indicated by an X-raypowder diffraction pattern having at least the d-spacings set forth inTable A, hereinafter, and have titanium atoms in the crystal lattice inthe form of Ti_(O) ₄ tetrahedra, preferably in an amount of at least one(1.0) TiO₄ tetrahedron per 10,000 Å³ :

                  TABLE A                                                         ______________________________________                                        d, (Å)   Relative Intensity                                               ______________________________________                                        14.1 ± 0.2                                                                              s                                                                8.6 ± 0.2 m                                                                7.4 ± 0.2 m                                                                5.6 ± 0.1 s                                                                4.7 ± 0.1 m                                                                4.4 ± 0.1 m                                                                3.8 ± 0.1 s                                                                3.3 ± 0.1 s                                                                2.8 ± 0.1 m                                                                ______________________________________                                    

(4) The x-ray powder diffraction pattern of the LZ-225 product whencompared to a reference sample of Y shows that the peak intensities aredecreased but there is no observable increase in the background due toamorphous zeolite or TiO₂. Since both oxygen and water capacities wereessentially maintained, the decreased x-ray intensity is believed to becaused by incorporation of the titanium ion into the structure of thestarting zeolite. The remaining aluminum is considered to be in theframework since the cation equivalent (M⁺ /Al) is essentially 1.0. Allof the properties measured are consistent with a highly crystallineproduct containing about 13 mole percent titanium substituted in thezeolitic framework.

EXAMPLE 2

(1) Ten grams of an ammonium-exchanged zeolite Y containing 43.5millimoles of aluminum as Al₂ O₃, were slurried in 100 ml of an aqueous3.5 molar solution of ammonium acetate at a temperature of 75° C.Because of the limited solubility of (NH₄)₃ FeF₆, the salt was added tothe zeolite-water slurry as crystals. The weight of added (NH₄)₃ FeF₆crystals was 5.41 grams and was an amount sufficient to replace 55% ofthe framework aluminum of the zeolite with iron. Following the additionof the (NH₄)₃ FeF₆ crystals, the reaction mixture was digested under anitrogen atmosphere at 75° C. for 48 hours. The reaction mixture wasthen filtered and washed with warm distilled water until qualitativetesting of the wash water was negative for both aluminum and fluorideions. The chemical analyses for the starting zeolite and the molecularsieve product (hereinafter referred to as "LZ-224") are set forth inTable 3:

                  TABLE 3                                                         ______________________________________                                                         Starting                                                                             LZ-224                                                                 Zeolite Y                                                                            Product                                               ______________________________________                                        Na.sub.2 O, weight percent                                                                       2.53     1.60                                              (NH.sub.4).sub.2 O, weight percent                                                               9.51     5.73                                              Fe.sub.2 O.sub.3, weight percent                                                                 --       16.92                                             Al.sub.2 O.sub.3, weight percent                                                                 22.18    12.60                                             SiO.sub.2, weight percent                                                                        64.38    65.78                                             F.sub.2, weight percent                                                                          --       0.20                                              Na.sup.+ /Al       0.19     0.21                                              NH.sub.4.sup.+ /Al 0.84     0.89                                              Cation Equivalent, M.sup.+ /Al                                                                   1.03     1.10                                              SiO.sub.2 Al.sub.2 O.sub.3                                                                       4.93     8.86                                              Si/(Al.sub.2 + Fe.sub.2)                                                                         4.93     5.77                                              ______________________________________                                    

A comparison of the properties of the LZ-224 molecular sieve productwith the starting zeolite Y is shown in Table 4.

                  TABLE 4                                                         ______________________________________                                                         Starting                                                                             LZ-224                                                                 Zeolite Y                                                                            Product                                               ______________________________________                                        X-Ray Crystallinity:                                                          % by Peak Intensity:                                                                             100      36                                                Unit Cell, a.sub.o in Å:                                                                     24.712   24.636                                            Crystal Collapse Temp.                                                                           890      892                                               °C. (DTA):                                                             Framework Infrared:                                                           Asymmetric Stretch, cm.sup.-1 :                                                                  1015     1028                                              Symmetric Stretch, cm.sup.-1 :                                                                   789      795                                               Hydroxyl Infrared:                                                            Absolute Absorbance                                                                              0.020    0.127                                             at 3710 cm.sup.-1 :                                                           Defect Structure   0.009    0.054                                             Factor, z:                                                                    McBain Adsorption:                                                            Wt. % O.sub.2, 100 torr.                                                                         35.2     25.4                                              -183° C.:                                                              Wt. % H.sub.2 O, 4.6 torr.                                                                       32.1     25.7                                              25° C.:                                                                ______________________________________                                    

(2) The framework mole fraction of tetrahedra are set forth below forthe starting zeolite Y and the LZ-224 molecular sieve product.

(a) Mole fraction of Oxides (TO₂): Starting Zeolite Y: (Al₀.286 Si₀.705[ ]₀.009)O₂ LZ-224 Product: (Al₀.150 Si₀.667 Fe₀.129 [ ]₀.054)O₂

(b) Mole fraction of aluminum removed, N: 0.136

(c) Percent aluminum removal, N/a×100: 48

(d) Change in Defect Structure Factor, Δz: 0.045

(e) Moles of titanium substituted per mole of aluminum removed: 0.95

(3) The molecular sieve's denominated herein as "LZ-224" have thecharacteristic crystal structure of zeolite Y as indicated by an X-raydiffraction pattern having at least the d-spacings set forth in Table B,hereinafter, and having iron atoms in the crystal lattice in the form of"FeO₄ " tetrahedra, preferably in an amount of at least one (1.0) FeO₄tetrahedron per 10,000 Å³ :

                  TABLE B                                                         ______________________________________                                        d, (Å)   Relative Intensity                                               ______________________________________                                        14.1 ± 0.2                                                                              s                                                                8.6 ± 0.2 m                                                                7.4 ± 0.2 m                                                                5.6 ± 0.1 m                                                                4.7 ± 0.1 m                                                                4.4 ± 0.1 m                                                                3.8 ± 0.1 m                                                                3.3 ± 0.1 m                                                                2.8 ± 0.1 m                                                                ______________________________________                                    

(4) In the present example there were no extraneous peaks observed inthe powder pattern of the LZ-224 product. The zeolite peaks weresomewhat broadened and substantially decreased in intensity as comparedto zeolite Y. There appears to be no overall increase in background dueto amorphous material. Since both oxygen and water capacities areessentially maintained, as compared with the starting zeolite, thedecreased x-ray peak intensity is believed to be caused by incorporationof iron into zeolite structure of LZ-224.

The above properties are consistent with a highly crystalline molecularsieve product containing 10 mole percent iron in the framework andadditional iron in a cationic form.

EXAMPLE 3

(1) Twenty-five grams of a hydronium-exchanged synthetic mordenite(ZEOLON (TM,, is a trademark of Norton Co.), containing 52.8 millimolesof aluminum as Al₂ O₃ were slurried in 450 ml distilled H₂ O. Because ofthe limited solubility of (NH₄)₂ TiF₆, the salt was added to the slurryas crystals. The weight of added (NH₄)₂ TiF₆ was 2.61 grams. This is anamount which is sufficient to replace 25% of the framework aluminum ofthe zeolite with titanium. The reaction mixture as then digested atreflux for 18 hours, filtered and washed with warm distilled water untiltesting of the wash water was negative for both aluminum and fluorideions. The chemical analyses for the starting mordenite and thetitanium-containing molecular sieve product (hereinafter referred to as"LZ-227") are set forth in Table 5 wherein this LZ-227 product isdesignated product A. A comparison of the properties of this LZ-227product (Product A) with the starting mordenite is shown in Table 6. Theframework mole fractions of tetrahedra are set forth below for thestarting mordenite and the LZ-227 molecular sieve product:

(a) Mole fraction of Oxides (TO₂): Starting mordenite: (Al₀.106 Si₀.740[ ]₀.154)O₂ LZ-227 Product A: (Al₀.072 Si₀.804 Ti₀.034 [ ]₀.090)O₂

(b) Mole fraction of aluminum removed, N: 0.034

(c) Percent aluminum removal, N/a×100: 32

(d) Change in Defect Structure Factor, Δz: -0.064

(e) Moles of titanium substituted per mole of aluminum removed: 1.00

(2) Twenty-five grams of hydronium-exchanged synthetic mordenite (ZEOLON(TM), from Norton Co.), containing 52.8 millimoles of aluminum, as Al₂O₃ were slurried in 450 ml of distilled H₂ O. Due to the limitedsolubility of (NH₄)₂ TiF₆, the salt was added to the slurry as crystals.The weight of added (NH₄)₂ TiF₆ was 5.22 grams and was an amountsufficient to replace 50% of the framework aluminum of the zeolite withtitanium. The reaction mixture was then digested at reflux for 30minutes, filtered and washed with warm distilled water until testing ofthe wash water was negative for both aluminum and fluoride ions. Thechemical analyses for the starting mordenite and the molecular sieveproduct (herein referred to as LZ-227) are set forth in Table 5 whereinthis LZ-227 product is designated product B. A comparison of theproperties of this LZ-227 product (Product B) with the startingmordenite and Product A is shown in Table 6. The framework molefractions of tetrahedra are set forth below for the starting mordeniteand the LZ-227 molecular sieve product:

(a) Mole fraction of Oxides (TO₂): Starting H Mordenite: (Al₀.106Si₀.740 [ ]₀.154)O₂ LZ-227 Product B: (Al₀.069 Si₀.748 Ti₀.023 []₀.160)O₂

(b) Mole fraction of aluminum removed, N: 0.037

(c) Percent aluminum removal, N/a×100: 35

(d) Change in Defect Structure Factor, Δz: 0.006

(e) Moles of titanium substituted per mole of aluminum removed: 0.62

(3) Twenty-five grams of a hydronium-exchanged synthetic mordenite(ZEOLON (TM), a trademark of Norton Co.), containing 52.8 millimoles ofaluminum as Al₂ O₃, were slurried in 450 ml distilled H₂ O. Because ofthe limited solubility of (NH₄)₂ TiF₆ the salt was added to the slurryas crystals. The weight of added (NH₄)₂ TiF₆ was 7.83 grams and was anamount sufficient to replace 75% of the framework aluminum withtitanium. The reaction mixture was then digested at reflux for 30minutes, filtered and washed with warm distilled water until testing ofthe wash water was negative for both aluminum and fluoride ions. Thechemical analyses for the starting mordenite and the molecular sieveproduct (referred to herein as LZ-227) are set forth in Table 5 whereinthis LZ-227 product is designated Product C. A comparison of theproperties of the LZ-227 product (Product C) with the starting mordeniteis shown in Table 6. The framework mole fraction of tetrahedra are setforth below for the starting mordenite and Product C:

(a) Mole fraction of Oxides (TO₂): Starting mordenite: (Al₀.106 Si₀.740[ ]₀.154)O₂ LZ-227 Product C: (Al₀.072 Si₀.776 Ti₀.024 [ ]₀.128)O₂

(b) Mole fraction of aluminum removed, N: 0.034

(c) Percent aluminum removal, N/a×100: 32

(d) Change in Defect Structure Factor, Δz: -0.026

(e) Moles of titanium substituted per mole of aluminum removed: 0.71

                  TABLE 5                                                         ______________________________________                                                          LZ-227   LZ-227   LZ-227                                              Starting                                                                              (Product (Product (Product                                            Mordenite                                                                             A)       B)       C)                                        ______________________________________                                        Na.sub.2 O, wt %                                                                          0.19      --       --     --                                      (NH.sub.4).sub.2 O, wt %                                                                  --        2.38     3.07   3.01                                    Fe.sub.2 O.sub.3, wt %                                                                    0.17      0.16     --     --                                      TiO.sub.2, wt %                                                                           0.97      4.65     3.52   3.46                                    Al.sub.2 O.sub.3, wt %                                                                    10.75     6.35     6.70   6.70                                    SiO.sub.2, wt %                                                                           88.77     83.79    86.25  85.16                                   F.sub.2, wt %                                                                             --        0.16     0.16   0.13                                    Na.sup.+ /Al                                                                              0.03      --       --     --                                      NH.sub.4.sup.+ /Al                                                                        --        0.74     0.90   0.88                                    Cation Equivalent                                                                         0.03      0.74     0.90   0.88                                    M.sup.+ /Al                                                                   SiO.sub.2 /Al.sub.2 O.sub.3                                                               14.00     22.38    21.81  21.57                                   Si/(Al.sub.2 + Ti.sub.2)                                                                  14.00     15.26    16.34  16.22                                   ______________________________________                                    

                  TABLE 6                                                         ______________________________________                                                          LZ-227   LZ-227   LZ-227                                              Starting                                                                              (Product (Product (Product                                            Mordenite                                                                             A)       B)       C)                                        ______________________________________                                        X-Ray Crystallinity                                                           % by Peak Intensity                                                                       100       87       109    106                                     % by Peak Area                                                                            100       82       109    108                                     Crystal Collapse                                                                          1010      1050     1022   1028                                    Temp: °C. (DTA)                                                                              1125     1140   1140                                    Framework                                                                     Infrared:                                                                     Asymmetric Stretch,                                                                       1073      1079     1075   1073                                    cm.sup.-1                                                                     Symmetric Stretch,                                                                        801       811      805    809                                     cm.sup.-1                                                                     Hydroxyl Infrared:                                                            Absolute    0.364     0.212    0.378  0.303                                   Absorbance                                                                    at 3710 cm.sup.-1                                                             Defect Structure                                                                          0.154     0.090    0.160  0.128                                   Factor, z                                                                     McBain Adsorption:                                                            Wt. % O.sub.2 100 torr.                                                                   19.1      18.8     18.4   16.6                                    -183° C.                                                               Wt. % H.sub.2 O, 4.6                                                                      16.2      13.3     16.6   17.4                                    torr. 25° C.                                                           ______________________________________                                    

(4) The molecular sieves denominated herein as "LZ-227" have thecharacteristic crystal structure of mordenite as indicated by an x-raydiffraction having at least the d-spacings set forth in Table C,hereinafter, and having titanium atoms in the crystal lattice in theform of TiO₄ tetrahedra, preferably in an amount of at least 1.0 per10,000 Å³ :

                  TABLE C                                                         ______________________________________                                        d (Å)    Relative Intensity                                               ______________________________________                                        13.5 ± 0.2                                                                              m                                                                9.0 ± 0.2 s                                                                6.5 ± 0.1 m                                                                4.5 ± 0.1 s                                                                4.0 ± 0.1 m                                                                3.8 ± 0.1 m                                                                3.5 ± 0.1 s                                                                3.4 ± 0.1 s                                                                3.2 ± 0.1 m                                                                ______________________________________                                    

(5) The x-ray powder pattern of LZ-227 Product A contained an extraneouspeak which was identified as Al(OH)₃ (gibbsite). The x-ray powderpatterns of Products B and C did not contain any extraneous peaks andthere was no observable increase in background due to the presence ofamorphous materials. Maintenance of both oxygen and water capacitiesdemonstrates the products are highly crystalline. The properties of theLZ-227 products indicate that the products contain titanium incorporatedinto the zeolite framework.

EXAMPLE 4

(1) Twenty-five grams of a hydronium-exchanged synthetic mordenite(ZEOLON (TM), is a trademark of Norton Co.), containing 52.8 millimolesof aluminum as Al₂ O₃ were slurried in 450 ml distilled H₂ O. Because ofthe limited solubility of (NH₄)₃ FeF₆, the salt was added to the slurryas crystals. The weight of added (NH₄)₃ FeF₆ was 2.95 grams and was anamount which is sufficient to replace 25% of the framework aluminum withiron. The reaction mixture was digested at reflux under a N₂ atmospherefor 48 hours, filtered and washed with warm distilled water untiltesting of the wash water was negative for both aluminum and fluorideions. The chemical analyses for the starting mordenite and the molecularsieve product zeolite (referred to as "LZ-226") are set forth in Table 7wherein this LZ-226 product is designated product A. A comparison of theproperties of Product A with the starting mordenite is shown in Table 8.The framework mole fractions of tetrahedra are set forth below for thestarting mordenite and Product A:

(a) Mole fraction of Oxides (TO₂): Starting mordenite: (Al₀.106 Si₀.740[ ]₀.154)O₂ LZ-226 Product A: (Al₀.080 Si₀.816 Fe₀.038 [ ]₀.066)O₂

(b) Mole fraction of aluminum removed, N: 0.026

(c) Percent aluminum removal, N/a×100: 25

(d) Change in Defect Structure Factor, Δz: -0.088

(e) Moles of iron substituted per mole of aluminum removed: 1.46

(2) Twenty-five grams of hydronium-exchanged synthetic mordenite (ZEOLON(TM), a trademark of Norton Co.), containing 52.8 millimoles ofaluminum, as Al₂ O₃ were slurried in 450 ml of distilled H₂ O. Due tothe limited solubility of Na₃ FeF₆, the salt was added as crystals. Theweight of added Na₃ FeF₆ was 5.91 grams and was an amount sufficient toreplace 50% of the framework aluminum with iron. The reaction mixturewas digested at reflux for 30 minutes under an atmosphere of N₂,filtered and washed with warm distilled water until testing of the washwater was negative for both aluminum and fluoride ions. The chemicalanalyses for the starting mordenite and the molecular sieve product(herein referred to as LZ-226) are set forth in Table 7 wherein thisLZ-226 product is designated product B. A comparison of the propertiesof product B with the starting mordenite is set forth in Table 8. Theframework mole fractions of tetrahedra are set forth below for thestarting mordenite and the LZ-226 product B:

(a) Mole fraction of Oxides (TO₂): Starting H Mordenite: (Al₀.106Si₀.740 [ ]₀.154)O₂ LZ-226, Product B: (Al₀.072 Si₀.761 Fe₀.035 []₀.132)O₂

(b) Mole fraction of aluminum removed, N: 0.034

(c) Percent aluminum removal, N/a×100: 32

(d) Change in Defect Structure Factor, Δz: -0.022

(e) Moles of iron substituted per mole of aluminum removed: 1.03

(3) Twenty-five grams of a hydronium-exchanged synthetic mordenite(ZEOLON (TM), a trademark of Norton Co.), containing 52.8 millimoles ofaluminum as Al₂ O₃, were slurried in 450 ml distilled H₂ O. Because ofthe limited solubility of Na₃ FeF₆, the salt was added to the slurry ascrystals. The weight of added salt was 8.86 grams was an amountsufficient to replace 75% of the framework aluminum with iron. Thereaction mixture was digested at reflux for 30 minutes under anatmosphere of N₂, filtered and washed with warm distilled water untiltesting of the wash water was negative for both aluminum and fluorideions. The chemical analyses for the starting mordenite and the molecularsieve product zeolite (referred to herein as LZ-226) are set forth inTable 7 wherein this LZ-226 product is designated Product C. Acomparison of the properties of this LZ-226 product (Product C) with thestarting mordenite is shown in Table 8. The framework mole fraction oftetrahedra are set forth below for the starting mordenite and thisLZ-226 product:

(a) Mole fraction of Oxides (TO₂): Starting mordenite: (Al₀.106 Si₀.740[ ]₀.154)O₂ LZ- 226, Product C: (Al₀.060 Si₀.705 Fe₀.049 [ ]₀.187)O₂

(b) Mole fraction of aluminum removed, N: 0.046

(c) Percent aluminum removal, N/a×100: 43

(d) Change in Defect Structure Factor, Δz: 0.033

(e) Moles of iron substituted per mole of aluminum removed: 1.07 PG,42

                  TABLE 7                                                         ______________________________________                                                          LZ-226   LZ-226   LZ-226                                              Starting                                                                              (Product (Product (Product                                            Mordenite                                                                             A)       B)       C)                                        ______________________________________                                        Na.sub.2 O, wt %                                                                          0.19      --       2.81   2.80                                    (NH.sub.4).sub.2 O, wt %                                                                  --        2.94     0.08   0.06                                    Fe.sub.2 O.sub.3, wt %                                                                    0.17      4.08     5.15   5.95                                    TiO.sub.2, wt %                                                                           0.97      0.46     --     --                                      Al.sub.2 O.sub.3, wt %                                                                    10.75     8.04     6.79   7.70                                    SiO.sub.2, wt %                                                                           88.77     87.20    84.92  83.38                                   F.sub.2, wt %                                                                             --        0.46     0.36   0.68                                    Na.sup.+ /Al                                                                              0.03      --       0.68   0.77                                    NH.sub.4.sup.+ /Al                                                                        --        0.72     0.02   0.02                                    Cation Equivalent                                                                         10.03     0.72     0.71   0.79                                    M.sup.+ /Al                                                                   SiO.sub.2 /Al.sub.2 O.sub.3                                                               14.00     18.39    21.22  23.79                                   Si/(Al.sub.2 + Fe.sub.2)                                                                  14.00     13.90    14.29  13.03                                   ______________________________________                                    

                  TABLE 8                                                         ______________________________________                                                          LZ-226   LZ-226   LZ-226                                              Starting                                                                              (Product (Product (Product                                            Mordenite                                                                             A)       B)       C)                                        ______________________________________                                        X-Ray Crystallinity:                                                          % by Peak Intensity                                                                       100       80       65*    56*                                     % by Peak Area                                                                            100       74       61     54                                      Crystal Collapse                                                                          1010      992, 1105                                                                              926    900**                                   Temp., °C. (DTA)                                                       Framework                                                                     Infrared:                                                                     Asymmetric Stretch,                                                                       1073      1072     1070   1078                                    cm.sup.-1                                                                     Symmetric Stretch,                                                                        801       811      809    808                                     cm.sup.-1                                                                     Hydroxyl Infrared:                                                            Absolute    0.364     0.155      0.312                                                                                0.440                                 Absorbance                                                                    at 3710 cm.sup.-1                                                             Defect Structure                                                                          0.154     0.066      0.132                                                                                0.187                                 Factor, z                                                                     McBain Adsorption:                                                            Wt. % O.sub.2 100 torr,                                                                   19.1      19.0     17.7   17.4                                    -183° C.                                                               Wt. % H.sub.2 O, 4.6                                                                      16.2      13.4     15.9   15.6                                    torr, 25° C.                                                           ______________________________________                                         *The xray powder pattern also showed the presence of --FeOOH, Iron            oxyhydroxide.                                                                 **approximately 900° C. ± 10° C.                        

The molecular sieves denominated herein as "LZ-226" have thecharacteristic crystal structure of mordenite as indicated by an x-raydiffraction pattern having at least the d-spacings set forth in Table D,below, and having iron atoms in the crystal lattice in the form of "FeO₄" tetrahedra, preferably in an amount of at least 1.0 per 10,000 Å³.

                  TABLE D                                                         ______________________________________                                        d (Å)    Relative Intensity                                               ______________________________________                                        13.5 ± 0.2                                                                              m                                                                9.0 ± 0.2 s                                                                6.5 ± 0.1 m                                                                4.5 ± 0.1 s                                                                4.0 ± 0.1 m                                                                3.8 ± 0.1 m                                                                3.5 ± 0.1 s                                                                3.4 ± 0.1 s                                                                3.2 ± 0.1 m                                                                ______________________________________                                    

(4) The x-ray powder patterns of the LZ-226, particularly those ofProducts B and C, contained several small peaks which were identified astrace quantities of β-iron oxyhydroxide (β-FeOOH). These two productswere prepared using the sodium salt of the iron fluoride.

EXAMPLE 5

(1) Seventy grams of an ammonium-exchanged zeolite L,

272.0 millimoles of aluminum as Al₂ O₃, were slurried in 500 mldistilled H₂ O. Because of the limited solubility of (NH₄)₂ TiF₆, thesalt was added to the slurry as crystals. The weight of added (NH₄)₂TiF₆ was 26.66 grams and was an amount sufficient to replace 50% of theframework aluminum with titanium. Following the addition of the (NH₄)₂TiF₆ crystals the reaction mixture was digested at reflux for 17 hours,filtered and washed with warm distilled water until testing of the washwater was negative for both aluminum and fluoride ions. The chemicalanalyses for the starting zeolite L and the molecular sieve product(referred to herein as "LZ-229" ) are set forth in Table 9 wherein thisLZ-229 product is designated Product A. A comparison of the propertiesof this LZ-229 product (Product A) with the starting zeolite L is shownin Table 10. The framework mole fractions of tetrahedra are set forthbelow for the starting zeolite L and this LZ-229 product.

(a) Mole fractions of oxides, (TO₂): Starting Zeolite NH₄ L: (Al₀.250Si₀.725 .sup.[ ]₀.025)O₂ LZ-229, Product A: (Al₀.136 Si₀.693 Ti₀.095.sup.[ ]₀.076)O₂.

(b) Mole fraction of aluminum removed, N: 0.136.

(c) Percent aluminum removed, N/a×100: 46.

(d) Change in Defect Structure Factor. Δz: 0.051.

(e) Moles of titanium substituted per mole of aluminum removed: 0.83.

(2) Twenty grams of an ammonium-exchanged zeolite L, containing 77.7millimoles of aluminum as Al₂ O₃ were slurried in 250 ml distilled H₂ O.Because of the limited solubility of (NH₄)₂ TiF₆, the salt was added tothe slurry as crystals. The weight of added (NH₄)₂ TiF₆ was 7.62 gramsand was an amount sufficient to replace 50% of the framework aluminumwith titanium. Following the addition of the (NH₄)₂ TiF₆ crystals thereaction mixture was digested at reflux for 30 minutes, filtered andwashed with warm distilled water until testing of the wash water wasnegative for both aluminum and fluoride ions. The chemical analyses forthe starting zeolite L and the molecular sieve product (referred toherein as "LZ-229") are set forth in Table 9 wherein this LZ-229 productis designated as Product B. A comparison of the properties of thisLZ-229 product (Product B) with the starting zeolite L is shown in Table10. The framework mole fractions of tetrahedra are set forth below forthe starting zeolite L and this LZ-229 product:

(a) Mole fractions of Oxides, (TO₂): Starting zeolite NH₄ L (Al₀.250Si₀.725 .sup.[ ]₀.025)O₂ LZ-229, Product B: (Al₀.205 Si₀.712 Ti₀.028.sup.[ ]₀.055)O₂.

(b) Mole fraction of aluminum removed. N: 0.045.

(c) Percent aluminum removed. N/a×100: 18

(d) Change in Defect Structure Factor. Δz: 0.030.

(e) Moles of titanium substituted per mole of aluminum removed: 0.62.

(3) Twenty grams of an ammonium-exchanged zeolite L, containing 77.7millimoles of aluminum as Al₂ O₃ were slurried in 250 ml distilled H₂ O.Because of the limited solubility of (NH₄)₂ TiF₆, the salt was added tothe slurry as crystals. The weight of added (NH₄)₂ TiF₆ was 11.43 gramsand was an amount sufficient to replace 75% of the framework aluminumwith titanium. The reaction mixture was digested at reflux for 30minutes, filtered and washed with warm distilled water until testing ofthe wash water was negative for both aluminum and fluoride ions. Thechemical analyses for the starting zeolite L and the molecular sieveproduct (referred to herein as LZ-229) are set forth in Table 9 whereinthis LZ-229 product is designated Product C. A comparison of theproperties of this LZ-229 product (Product C) with the starting zeoliteL is shown in Table 10.

The framework mole fractions of tetrahedra are set forth below for thestarting zeolite L and this LZ-229 product.

(a) Mole fractions of Oxides, (TO₂): Starting NH₄ L: (Al₀.250 Si₀.725.sup.[ ]₀.025)O₂ LZ-229, Product C (Al₀.187 Si₀.688 Ti₀.054 .sup.[]₀.071)O₂.

(b) Mole fraction of aluminum removed, N: 0.063

(c) Percent aluminum removed. N/a×100: 25

(d) Change in Defect Structure Factor. Δz: 0.046.

(e) Moles of Titanium substituted per mole of aluminum removed: 0.86.

                  TABLE 9                                                         ______________________________________                                                          LZ-229   LZ-229   LZ-229                                              Starting                                                                              (Product (Product (Product                                            zeolite L                                                                             A)       B)       C)                                        ______________________________________                                        Na.sub.2 O, wt %                                                                          --        --       0.08   --                                      (NH.sub.4).sub.2 O, wt %                                                                  7.88      4.67     6.94   6.83                                    K.sup.+ Al  0.12      0.15     0.13   0.13                                    K.sub.2 O, wt %                                                                           2.20      1.59     1.97   1.94                                    TiO.sub.2, wt %                                                                           --        12.64    3.54   7.17                                    Al.sub.2 O.sub.3, wt %                                                                    19.81     11.85    16.88  15.72                                   Si.sub.2 O, wt %                                                                          67.76     69.25    68.90  68.34                                   F.sub.2, wt %                                                                             --        0.42     0.13   0.24                                    Na.sup.+ /Al                                                                              --        --       0.01   --                                      NH.sub.4.sup.+ /Al                                                                        0.78      0.77     0.81   0.85                                    Cation Equivalent,                                                                        0.90      0.92     0.94   0.98                                    M.sup.+ /Al                                                                   SiO.sub.2 /Al.sub.2 O.sub.3                                                               5.80      9.92     6.93   7.37                                    Si/(Al.sub.2 + Ti.sub.2)                                                                  5.80      6.01     6.11   5.71                                    ______________________________________                                    

                  TABLE 10                                                        ______________________________________                                                          LZ-229   LZ-229   LZ-229                                              Starting                                                                              (Product (Product (Product                                            Mordenite                                                                             A)       B)       C)                                        ______________________________________                                        X-Ray Crystallinity:                                                          % by Peak Intensity                                                                        100       44       73     73                                     % by Peak Area                                                                             100       44       74     74                                     Crystal Collapse                                                                           870,      900      870,   870,                                   Temp., °C. (DTA)                                                                   1132                972,  1000,                                                                  1132   1145                                    Framework                                                                     Infrared:                                                                     Asymmetric Stretch,                                                                       1100,     1111,    1100,  1104,                                   cm.sup.-1   1031      1035     1062,  1064,                                                                  1032   1033                                    Symmetric Stretch,                                                                         770,      777,     773,   774,                                   cm.sup.-1    726       725      732    727                                    Hydroxyl Infrared:                                                            Absolute      0.058     0.180    0.130                                                                                0.167                                 Absorbance                                                                    at 3710 cm.sup.-1                                                             Defect Structure                                                                            0.025     0.076    0.055                                                                                0.071                                 Factor, z                                                                     McBain Adsorption:                                                            Wt. % O.sub.2 ,                                                                            16.46     11.19    15.54  15.78                                  -183° C., 100 torr.                                                    Wt. % H.sub.2 O,                                                                           19.05     13.52    18.83  19.55                                  torr. 25° C.                                                           ______________________________________                                         (4) The molecular sieves denominated herein as "LZ-229" have the     characteristic crystal structure of zeolite L as indicated by an X-ray     diffraction pattern having at least the d-spacings set forth in Table E,     below, and having titanium atoms in the crystal lattice in the form of     TiO.sub.4 tetrahedra, preferably in an amount of at least 1.0 per 10,000     Å.sup.3 :

                  TABLE E                                                         ______________________________________                                        d (Å)    Relative Intensity                                               ______________________________________                                        15.8 ± 0.2                                                                              s                                                                6.0 ± 0.1 m                                                                5.8 ± 0.1 mw                                                               4.6 ± 0.1 m                                                                4.4 ± 0.1 mw                                                               4.3 ± 0.1 mw                                                               3.9 ± 0.1 m                                                                3.66 ± 0.1                                                                              m                                                                3.48 ± 0.1                                                                              m                                                                3.28 ± 0.1                                                                              mw                                                               3.18 ± 0.1                                                                              m                                                                3.07 ± 0.1                                                                              m                                                                2.91 ± 0.1                                                                              m                                                                ______________________________________                                    

EXAMPLE 6

(1) Seventy grams of an ammonium-exchanged zeolite L containing 272.0millimoles of aluminum, as Al₂ O₃, were slurried in 500 ml distilled H₂O. Because of the limited solubility of (NH₄)₃ FeF₆, the salt was addedto the slurry as crystals. The weight of added (NH₄)₃ FeF₆ was 30.16grams and was an amount sufficient to replace 50% of the zeoliticaluminum with iron. The reaction mixture was then digested at reflux for2 hours, under an atmosphere of N₂, filtered and washed with warmdistilled water until testing of the wash water was negative for bothaluminum and fluoride ions. The chemical analyses for the startingzeolite L and the molecular sieve product (referred to herein as"LZ-228") are set forth in Table 11 wherein this LZ-228 product isdesignated Product A. A comparison of the properties of this LZ-228product (Product A) with the starting zeolite L is shown in Table 12.

The framework mole fractions of tetrahedra are set forth below for thestarting zeolite L and this LZ-228 product:

(a) Mole fractions of Oxides, (TO₂): Starting zeolite NH₄ L: (Al₀.250Si₀.725 .sup.[ ]₀.025)O₂ LZ-228, Product A: (Al₀.172 Si₀.664 Fe₀.109.sup.[ ]₀.055)O₂.

(b) Mole fraction of Aluminum Removed. N: 0.078.

(c) Percent aluminum removed. N/a×100: 31.

(d) Change in Defect Structure Factor Δz: 0.030.

(e) Moles of Iron substituted per mole of aluminum removed: 1.40.

(2) Twenty grams of an ammonium-exchanged zeolite L, containing 77.7millimoles of aluminum, as Al₂ O₃, were slurried in 250 ml distilled H₂O. Because of the limited solubility of (NH₄)₃ FeF₆, the salt was addedto the slurry as crystals. The weight of added (NH₄)₃ FeF₆ was 8.62grams and was an amount sufficient to replace 50% of the zeolitesaluminum with iron. The reaction mixture was then digested at reflux for30 minutes under an atmosphere of N₂, filtered and washed with warmdistilled water until testing of the wash water was negative for bothaluminum and fluoride ions. The chemical analyses for the startingzeolite NH₄ L and the molecular sieve product (referred to herein as"LZ-228") are set forth in Table 11 wherein this LZ-228 product isdesignated Product B. A comparison of the properties of this LZ-228product (Product B) with the starting zeolite L is shown in Table 12.

The framework mole fractions of the tetrahedra are set forth below forthe starting zeolite L and this LZ-228 product

(a) Mole fractions of Oxides, (TO₂): Starting zeolite NH₄ L: (Al₀.250Si₀.725 .sup.[ ]₀.025)O₂ LZ-228, Product B: (Al₀.173 Si₀.652Fe₀.117.sup.[ ]₀.058)O₂.

(b) Mole fraction of Aluminum Removed, N: 0.077

(c) Percent aluminum removed, N/A×100: 31.

(d) Change in Defect Structure Factor Δz: 0.035.

(e) Moles of Iron substituted per mole of aluminum removed: 1.52.

(3) Twenty grams of an ammonium-exchanged zeolite L containing 77.7millimoles of aluminum, as Al₂ O₃, were slurried in 250 ml distilled H₂O. Because of the limited solubility of (NH₄)₃ FeF₆, the salt was addedto the slurry as crystals. The weight of added (NH₄)₃ FeF₆ was 12.93grams and was an amount sufficient to replace 75% of the zeoliticaluminum with iron. The reaction mixture was then digested at reflux for30 minutes under a protective atmosphere of N₂, filtered and washed withwarm distilled water until testing of the wash water was negative forboth aluminum and fluoride ions. The chemical analyses for the startingzeolite L and the LZ-228 product (designated Product C) are set forth inTable 11. A comparison of the properties of this LZ-228 product (ProductC) with the starting zeolite L is shown in Table 12.

The framework mole fractions of tetrahedra are set forth below for thestarting zeolite L and this LZ-228 product:

(a) Mole fractions of Oxides, (TO₂): Starting zeolite NH₄ L: (Al₀.250Si₀.725 .sup.[ ]₀.025)O₂ LZ-228, Product C: (Al₀.156 Si₀.616 Fe₀.098.sup.[ ]₀.130)O₂.

(b) Mole fraction of aluminum removed. N: 0.094.

(c) Percent aluminum removed, N/A×100: 38.

(d) Change in Defect Structure Factor Δz: 0.105.

(e) Moles of iron substituted per mole of aluminum removed: 0.104.

                  TABLE 11                                                        ______________________________________                                                          LZ-228   LZ-228   LZ-228                                               Starting                                                                             (Product (Product (Product                                             Zeolite L                                                                            A)       B)       C)                                        ______________________________________                                        Na.sub.2 O, wt %                                                                           --       --       --     0.79                                    (NH.sub.4).sub.2), wt %                                                                    7.88     5.63     5.85   5.17                                    K.sub.2 O, wt %                                                                            2.20     1.72     1.64   1.88                                    Fe.sub.2 O.sub.3, wt %                                                                     --       13.91    15.10  13.51                                   Al.sub.2 O.sub.3, wt %                                                                     19.81    14.02    15.11  13.63                                   SiO.sub.2, wt %                                                                            67.76    63.79    63.58  63.57                                   F.sub.2, wt %                                                                              --       1.05     0.91   0.93                                    NH.sub.4.sup.+ /Al                                                                         0.78     0.79     0.80   0.74                                    K.sup.+ /Al  0.12     0.13     0.12   0.15                                    Cation Equivalent,                                                                         0.90     0.92     0.93   0.99                                    M.sup.+ /Al                                                                   SiO.sub.2 /Al.sub.2 O.sub.3                                                                5.80     7.72     7.55   7.91                                    Si/(Al.sub.2 + Fe.sub.2)                                                                   5.80     4.73     4.51   4.85                                    ______________________________________                                    

                  TABLE 12                                                        ______________________________________                                                         LZ-228   LZ-228   LZ-228                                               Starting                                                                             (Product (Product (Product                                             Zeolite L                                                                            A)       B)       C)                                         ______________________________________                                        X-Ray Crystallinity:                                                          % by Peak Intensity                                                                        100      33       46     46                                      % by Peak Area                                                                             100      35       46     48                                      Crystal Collapse                                                                           870,     840      845    855                                     Temp., °C. (DTA)                                                                   1132                                                              Framework                                                                     Infrared:                                                                     Asymmetric Stretch,                                                                       1100,    1105,    1105,  1099,                                    cm.sup.-1   1031     1062,    1064,  1065,                                                         1033     1042   1031                                     Symmetric Stretch,                                                                         770,     776,     774,   772,                                    cm.sup.-1    726      724      723    724                                     Hydroxyl Infrared:                                                            Absolute      0.058    0.130    0.138                                                                                0.307                                  Absorbance                                                                    at 3710 cm.sup.-1                                                             Defect Structure                                                                            0.025    0.055    0.058                                                                                0.130                                  Factor, z                                                                     McBain Adsorption:                                                            wt % O.sub.2                                                                               16.46    13.57    13.38  16.76                                   -183° C., 100 torr                                                     wt % H.sub.2 O,                                                                            19.05    15.32    17.19  20.30                                   4.6 torr. 25° C.                                                       ______________________________________                                    

(4) The molecular sieves denominated herein as "LZ-228" have thecharacteristic crystal structure of zeolite L as indicated by an X-raypowder diffraction pattern having at least the d-spacings set forth inTable F below, and having iron atoms in the crystal lattice in the formof FeO₄ tetrahedra, preferably in an amount of at least 1.0 per 10,000Å³.

                  TABLE F                                                         ______________________________________                                        d(Å)     Relative Intensity                                               ______________________________________                                        15.8 ± 0.2                                                                              s                                                                6.0 ± 0.1 m                                                                5.8 ± 0.1 mw                                                               4.6 ± 0.1 m                                                                4.4 ± 0.1 mw                                                               4.3 ± 0.1 mw                                                               3.9 ± 0.1 m                                                                3.66 ± 0.1                                                                              m                                                                3.48 ± 0.1                                                                              m                                                                3.28 ± 0.1                                                                              mw                                                               3.18 ± 0.1                                                                              m                                                                3.07 ± 0.1                                                                              mw                                                               2.91 ± 0.1                                                                              m                                                                ______________________________________                                    

(5) Fluoresence by the heavier iron atoms would account for the reducedX-ray crystallinity. A probative measure of the retained crystallinityand void volume of iron-containing product is available from the H₂ Oand O₂ adsorption capacities which indicate that the products werehighly crystalline. All properties taken together indicate that iron hasbeen incorporated into the framework of the zeolite L as both cation andtetrahedral atom.

EXAMPLE 7

1. Ten grams of an ammonium-exchanged, natural mineral clinoptilolite,containing 25.1 millimoles of aluminum as Al₂ O₃, were slurried in 250ml distilled H₂ O. Because of the limited solubility of (NH₄)₂ TiF₆, thesalt was added to the slurry as crystals. The weight of added (NH₄)₂TiF₆ was 2.49 grams and was an amount sufficient to replace 50% of theframework aluminum of the zeolite with titanium. The reaction mixturewas refluxed for 30 minutes, filtered and washed with warm distilledwater until testing of the wash water was negative for both aluminum andfluoride ions. The chemical analyses for the starting clinoptilolite andthe molecular sieve product (referred to herein as LZ-231) are set forthin Table 13.

                  TABLE 13                                                        ______________________________________                                                        Starting LZ-231                                                               Clinoptilolite                                                                         Product                                              ______________________________________                                        Na.sub.2 O, weight percent                                                                      0.55       0.45                                             (NH.sub.4).sub.2 O, weight percent                                                              5.19       4.84                                             K.sub.2 O, weight percent                                                                       0.77       0.54                                             TiO.sub.2, weight percent                                                                       --         3.08                                             Al.sub.2 O.sub.3, weight percent                                                                12.82      12.10                                            SiO.sub.2, weight percent                                                                       77.90      75.69                                            F.sub.2, weight percent                                                                         --         0.19                                             Na.sup.+ /Al:     0.07       0.06                                             NH.sub.4.sup.+ /Al:                                                                             0.79       0.78                                             K.sup.+ /Al:      0.07       0.05                                             Cation Equivalent,                                                                              0.93       0.89                                             M.sup.+ /Al:                                                                  SiO.sub.2 /Al.sub.2 O.sub.3 :                                                                   10.31      10.61                                            Si/(Al.sub.2 + Ti.sub.2):                                                                       10.31      9.31                                             ______________________________________                                    

                  TABLE 14                                                        ______________________________________                                                       Starting   LZ-231                                                             Clinoptilolite                                                                           Product                                             ______________________________________                                        X-Ray Crystallinity:                                                          % by Peak Intensity                                                                             100          75                                             % by Peak Area:   100          75                                             Crystal Collapse  528         None                                            Temp., °C. (DTA):      Observed                                        Framework Infrared:                                                           Assymmetric Stretch,                                                                           1082         1065                                            cm.sup.-1 :                                                                   Symmetric Stretch,                                                                              795,         797,                                           cm.sup.-1 :       778          778                                            Hydroxyl Infrared:                                                            Absolute Absorbance                                                                              0.055        0.080                                         3710.sup.-1                                                                   Defect Structure   0.023        0.034                                         Factor, z:                                                                    McBain Adsorption:                                                            wt % O.sub.2, 100 torr.                                                                         15.10        15.26                                          -183° C.:                                                              wt. % H.sub.2 O,  11.66        14.80                                          4.6 torr. 25° C.:                                                      ______________________________________                                    

The framework mole fractions of tetrahedra are set forth below for thestarting NH₄ clinoptilolite and the LZ-231 product:

(a) Mole fractions of oxides (TO₂ O): Starting NH₄ clinoptilolite:(Al₀.159 Si₀.818 .sup.[ ]₀.023)O₂ LZ-231 product: (Al₀.150 Si₀.792Ti₀.024 .sup.[ ]₀.034)O₂.

(b) Mole fraction of aluminum removed, N: 0.009.

(c) Percent aluminum removed, N/a×100: 6.

(d) Change in Defect Structure Factor: Δz: 0.011.

(e) Moles of titanium substituted per mole of aluminum removed: 2.67.

(2) The molecular sieves denominated herein as "LZ-231" have thecharacteristic crystal structure of zeolite clinoptilolite as indicatedby an X-ray powder diffraction pattern having at least the d-spacingsset forth in Table G below and having titanium atoms in the crystallattice in the form of TiO₄ tetrahedra, preferably in an amount of atleast 1.0 per 10,000 Å³.

                  TABLE G                                                         ______________________________________                                        d(Å)     Relative Intensity                                               ______________________________________                                        8.9 ± 0.2 vs                                                               7.8 ± 0.2 m                                                                6.7 ± 0.2 mw                                                               6.6 ± 0.2 mw                                                               5.1 ± 0.2 mw                                                               3.95 ± 0.1                                                                              ms                                                               3.89 ± 0.1                                                                              m                                                                3.41 ± 0.1                                                                              m                                                                3.37 ± 0.1                                                                              mw                                                               3.33 ± 0.1                                                                              m                                                                3.17 ± 0.1                                                                              mw                                                               ______________________________________                                    

(3) When all of the properties of the LZ-231 of this example areconsidered, it was concluded that the 3.08 weight percent TiO₂ indicatesthat titanium was incorporated into the framework of the clinoptilolite.

EXAMPLE 8

(1) Ten grams of an ammonium-exchanged synthetic TMA offretitecontaining 27.6 millimoles of aluminum as Al₂ O₃, were slurried in 250ml distilled H₂ O. Because of the limited solubility of (NH₄)₂ TiF₆, thesalt was added to the slurry as crystals. The weight of added (NH₄)₂TiF₆ was 2.73 grams and was an amount sufficient to replace 50% of thealuminum of the zeolite with titanium. The reaction mixture was refluxedfor 30 minutes, filtered and washed with warm distilled water untiltesting of the wash water was negative for both aluminum and fluorideions. The chemical analyses for the starting offretite and the product(referred to herein as "LZ-233") are set forth in Table 15:

                  TABLE 15                                                        ______________________________________                                                         Starting                                                                             LZ-233                                                                 Offretite                                                                            Product                                               ______________________________________                                        Na.sub.2 O, weight percent                                                                       --       --                                                (NH.sub.4).sub.2 O, weight percent                                                               5.31     5.02                                              K.sub.2 O, weight percent                                                                        2.48     2.10                                              TiO.sub.2, weight percent                                                                        --       2.80                                              Al.sub.2 O.sub.3, weight percent                                                                 14.05    12.72                                             SiO.sub.2, weight percent                                                                        76.15    76.90                                             F.sub.2, weight percent                                                                          --       0.11                                              Na.sup.+ /Al:      --       --                                                NH.sub.4.sup.+ /Al:                                                                              0.74     0.77                                              K.sup.+ /Al:       0.19     0.18                                              Cation Equivalent, M.sup.+ /Al:                                                                  0.93     0.95                                              SiO.sub.2 /Al.sub.2 O.sub.3 :                                                                    9.20     10.26                                             Si/(Al.sub.2 + Ti.sub.2):                                                                        9.20     9.00                                              ______________________________________                                    

A comparison of the properties of the LZ-233 product with the startingoffretite is shown in Table 16:

                  TABLE 16                                                        ______________________________________                                                        Starting                                                                             LZ-233                                                                 Offretite                                                                            Product                                                ______________________________________                                        X-Ray Crystallinity:                                                          % by Peak Intensity                                                                             100      85                                                 % by Peak Area:   100      87                                                 Crystal Collapse  1001     1010                                               Temp., °C. (DTA):                                                      Framework Infrared:                                                           Asymmetric Stretch,                                                                             1083     1085                                               cm.sup.-1 :                                                                   Symmetric Stretch,                                                                              789      791                                                cm.sup.-1 :                                                                   Hydroxyl Infrared:                                                            Absolute Absorbance                                                                             0.140    0.116                                              3710.sup.-1                                                                   Defect Structure  0.059    0.049                                              Factor, z:                                                                    McBain Adsorption:                                                            wt % O.sub.2, 100 torr.                                                                         25.33    24.60                                              -183° C.:                                                              wt. % H.sub.2 O,  21.10    23.94                                              4.6 torr. 25° C.:                                                      ______________________________________                                    

The framework mole fractions of tetrahedra are set forth below for thestarting offretite LZ-233 product:

(a) Mole fractions of oxide (TO₂ O: Starting NH₄ Offretite: (Al₀.168Si₀.773 .sup.[ ]₀.059)O₂ LZ-233 product: (Al₀.152 Si₀.778 Ti₀.021 .sup.[]₀.049)O₂.

(b) Mole fraction of aluminum removed, N: 0.016.

(c) Percent aluminum removed, N/z×100: 10.

(d) Change in Defect Structure Factor, Δz: -0.010.

(e) Moles of titanium substituted per mole of aluminum removed: 1.31.

(2) The molecular sieves denominated herein as "LZ-233" have thecharacteristic crystal structure of zeolite offretite as indicated by anX-ray powder diffraction pattern having at least the d-spacings setforth in Table H below and having titanium atoms in the crystal latticein the form of TiO₄ tetrahedra, preferably in an amount of at least 1.0per 10,000 Å³.

                  TABLE H                                                         ______________________________________                                        d(Å)     Relative Intensity                                               ______________________________________                                        11.4 ± 0.2                                                                              vs                                                                6.6 ± 0.1                                                                              ms                                                                5.7 ± 0.1                                                                              mw                                                               4.31 ± 0.1                                                                              m                                                                3.75 ± 0.1                                                                              m                                                                3.58 ± 0.1                                                                              m                                                                3.29 ± 0.1                                                                              mw                                                               3.14 ± 0.1                                                                              mw                                                               2.84 ± 0.1                                                                              m                                                                2.67 ± 0.1                                                                              mw                                                               ______________________________________                                    

(3) When all the aforementioned properties are considered together suchare consistent with the conclusion that the 2.80 weight percent TiO₂found in the LZ-233 product represents titanium incorporated into theframework of the offretite.

EXAMPLE 9

(1) Ten grams of an ammonium-exchanged, natural mineral erionitecontaining 33.0 millimoles of aluminum, as Al₂ O₃, were slurried in 250ml distilled H₂ O. Because of the limited solubility of (NH₄)₂ TiF₆, thesalt was added to the slurry as crystals. The weight of added (NH₄)₂TiF₆ was 3.26 grams and was an amount sufficient to replace 50% of thealuminum of the zeolites with titanium. The reaction mixture wasrefluxed for 30 minutes, filtered and washed with warm distilled wateruntil tests of the wash water were negative for both aluminum andfluoride ions. The chemical analyses for the starting NH₄ erionite andthe molecular sieve product (referred to herein as "LZ-232" are setforth in Table 17.

                  TABLE 17                                                        ______________________________________                                                         Starting                                                                             LZ-232                                                                 Erionite                                                                             Product                                               ______________________________________                                        Na.sub.2 O, weight percent                                                                       0.35     0.23                                              (NH.sub.4).sub.2 O, weight percent                                                               5.75     5.37                                              K.sub.2 O, weight percent                                                                        3.22     3.09                                              Fe.sub.2 O.sub.3, weight percent                                                                 0.99     --                                                TiO.sub.2, weight percent                                                                        --       1.14                                              Al.sub.2 O.sub.3, weight percent                                                                 16.80    16.00                                             SiO.sub.2, weight percent                                                                        68.93    70.63                                             F.sub.2, weight percent                                                                          --       0.08                                              Na.sup.+ /Al:      0.03     0.02                                              NH.sub.4.sup.+ /Al:                                                                              0.67     0.66                                              K.sup.+ /Al:       0.21     0.21                                              Cation Equivalent, M.sup.+ /Al:                                                                  0.91     0.89                                              SiO.sub.2 /Al.sub.2 O.sub.3 :                                                                    6.96     7.49                                              Si/(Al.sub.2 + Ti.sub.2):                                                                        6.96     7.16                                              ______________________________________                                    

A comparison of the properties of the LZ-232 product with the startingerionite is shown in Table 18:

                  TABLE 18                                                        ______________________________________                                                        Starting                                                                             LZ-232                                                                 Erionite                                                                             Product                                                ______________________________________                                        X-Ray Crystallinity:                                                          % by Peak Intensity                                                                             100      172                                                % by Peak Area:   100      155                                                Crystal Collapse  975      985                                                Temp., °C. (DTA):                                                      Framework Infrared:                                                           Assymmetric Stretch,                                                                            1052     1070                                               cm.sup.-1 :                                                                   Symmetric Stretch,                                                                              781      782                                                cm.sup.-1 :                                                                   Hydroxyl Infrared:                                                            Absolute Absorbance                                                                             0.070    0.060                                              3710 cm.sup.-1                                                                Defect Structure  0.030    0.026                                              Factor, z:                                                                    McBain Adsorption:                                                            wt % O.sub.2, 100 torr.                                                                         17.75    18.58                                              -183° C.:                                                              wt. % H.sub.2 O,  16.47    18.08                                              4.6 torr. 25° C.:                                                      ______________________________________                                    

The framework mole fractions of tetrahedra are set forth below for thestarting NH₄ erionite and the LZ-232 product:

(a) Mole fractions of oxides (TO₂): Starting erionite: (Al₀.217 Si₀.753.sup.[ ]₀.030)O₂ LZ-232 product: (Al₀.202 Si₀.763 Ti₀.009 .sup.[]₀.026)O₂.

(b) Mole fraction of aluminum removed, N: 0.015.

(c) Percent aluminum removed, N/a×100: 7

(d) Change in Defect Structure Factor, Δz: -0.004.

(e) Moles of titanium substituted per mole of aluminum removed: 0.60

(2) The molecular sieves denominated herein as "LZ-232" have thecharacteristic crystal structure of zeolite erionite as indicated by anX-ray powder diffraction pattern having at least the d-spacings setforth in Table J below and having titanium atoms in the crystal latticein the form of TiO₄ tetrahedra, preferably in an amount of at least 1.0per 10,000 Å³.

                  TABLE J                                                         ______________________________________                                        d(Å)     Relative Intensity                                               ______________________________________                                        11.3 ± 0.5                                                                              vs                                                                6.6 ± 0.2                                                                              s                                                                4.33 ± 0.1                                                                              m                                                                3.82 ± 0.1                                                                              m                                                                3.76 ± 0.1                                                                              m                                                                3.31 ± 0.1                                                                              m                                                                2.86 ± 0.1                                                                              m                                                                2.81 ± 0.1                                                                              m                                                                ______________________________________                                    

EXAMPLE 10

(1) Twenty grams of an ammonium-exchanged synthetic zeolite W,containing 120.9 millimoles of aluminum, as AL₂ O₃, were slurried in 500ml distilled H₂ O. Because of the limited solubility of (NH₄)₂ TiF₆, thesalt was added to the slurry as crystals. The weight of added (NH₄)₂TiF₆ was 12.40 grams and was an amount sufficient to replace 52% of thealuminum of the zeolite with titanium. The reaction mixture was thenrefluxed for 30 minutes, filtered and washed with warm distilled wateruntil testing of the wash water was negative for both aluminum andfluoride ions.

The chemical analyses for the starting zeolite W and the molecular sieveproduct (referred to herein as LZ-230) are set forth in Table 19.

                  TABLE 19                                                        ______________________________________                                                         Starting                                                                             LZ-230                                                                 NH.sub.4 W                                                                           Product                                               ______________________________________                                        Na.sub.2 O, weight percent                                                                       0.04     0.06                                              (NH.sub.4).sub.2 O, weight percent                                                               10.50    7.81                                              K.sub.2 O, weight percent                                                                        0.08     0.09                                              TiO.sub.2, weight percent                                                                        --       16.09                                             Al.sub.2 O.sub.3, weight percent                                                                 30.82    16.69                                             SiO.sub.2, weight percent                                                                        67.29    58.93                                             F.sub.2, weight percent                                                                          --       0.14                                              Na.sup.+ /Al:      0.01     0.01                                              NH.sub.4.sup.+ /Al:                                                                              0.68     0.92                                              K.sup.+ /Al:       0.01     0.01                                              Cation Equivalent, 0.70     0.93                                              M.sup.+ /Al:                                                                  SiO.sub.2 /Al.sub.2 O.sub.3 :                                                                    3.71     5.99                                              Si/(Al.sub.2 + Ti.sub.2):                                                                        3.71     3.71                                              ______________________________________                                    

A comparison of the properties of the LZ-230 product with the startingNH₄ W is shown in Table 20:

                  TABLE 20                                                        ______________________________________                                                        Starting                                                                             LZ-230                                                                 NH.sub.4 W                                                                           Product                                                ______________________________________                                        X-Ray Crystallinity:                                                          % by Peak Intensity                                                                             100      38                                                 % by Peak Area:   100      38                                                 Crystal Collapse  1030     1010                                               Temp., °C. (DTA):                                                      Framework Infrared:                                                           Assymmetric Stretch,                                                                            1023     1035                                               cm.sup.-1 :                                                                   Symmetric Stretch,                                                                              783,761  784,761                                            cm.sup.-1 :                                                                   Hydroxyl Infrared:                                                            Absolute Absorbance                                                                             0.053    0.269                                              3710 cm.sup.-1                                                                Defect Structure  0.023    0.114                                              Factor, z:                                                                    McBain Adsorption:                                                            wt % O.sub.2, 100 torr.                                                                         0        5.21                                               -183° C.:                                                              wt. % H.sub.2 O,  1.28     10.26                                              4.6 torr. 25° C.:                                                      ______________________________________                                    

The framework mole fractions of tetrahedra are set forth below for thestarting NH₄ W erionite and the LZ-230 product:

(a) Mole fractions of oxides (TO₂): Starting NH₄ W: (Al₀.343 Si₀.634.sup.[ ]₀.023)O₂ LZ-230 product: (Al₀.192 Si₀.576 Ti₀.118 .sup.[]₀.114)O₂.

(b) Mole fraction of aluminum removed, N: 0.151.

(c) Percent aluminum removed, N/a×100: 44

(d) Change in Defect Structure Factor, Δz: 0.091.

(e) Moles of titanium substituted per mole of aluminum removed: 0.78

(2) The molecular sieves denominated herein as "LZ-230" have thecharacteristic crystal structure of zeolite W as indicated by an X-raypowder diffraction pattern having at least the d-spacings set forth inTable K below and having titanium atoms in the crystal lattice in theform of TiO₄ tetrahedra, preferably in an amount of at least 1.0 per10,000 Å³.

                  TABLE K                                                         ______________________________________                                        d(Å)     Relative Intensity                                               ______________________________________                                         8.2 ± 0.2                                                                              ms                                                                7.1 ± 0.2                                                                              vs                                                                5.3 ± 0.1                                                                              ms                                                                5.0 ± 0.1                                                                              ms                                                                4.5 ± 0.1                                                                              mw                                                               4.31 ± 0.1                                                                              mw                                                               3.67 ± 0.1                                                                              mw                                                               3.25 ± 0.1                                                                              s                                                                3.17 ± 0.1                                                                              s                                                                2.96 ± 0.1                                                                              m                                                                2.73 ± 0.1                                                                              m                                                                2.55 ± 0.1                                                                              mw                                                               ______________________________________                                    

(3) The measured low X-ray crystallinity of the LZ-230 product shown inTable 20 is inconsistent with the measured increase in adsorptioncapacity for O₂ and H₂ O. All properties taken together lead to theconclusion that the 16.09 weight percent TiO₂ found in the LZ-230product represents titanium incorporated into the zeolite W framework.

EXAMPLE 10

Products of Examples 1, 2, 3, 4, 5 and 6 were tested for n-butanecracking activity and found to be active catalysts. The results of thosetests are shown in Tables 21, 22 and 23.

                  TABLE 21                                                        ______________________________________                                                               Consumption                                            Product   Example      of n-Butane                                                                              k.sub.a *                                   ______________________________________                                        NH.sub.4 Y                                                                              --           11.1       1.9                                         NH.sub.4 Y                                                                              --           29.5       4.3                                         LZ-224    2            14.0       6.4                                         LZ-225    1            2.0        3.9                                         ______________________________________                                         *The lower the value for k.sub.a the lower the activity.                 

                  TABLE 22                                                        ______________________________________                                                               Consumption                                            Product     Example    of n-Butane                                                                              k.sub.a *                                   ______________________________________                                        NH.sub.4 Mordenite                                                                        --         77.3       177                                         LZ-226      4          13.3       5.2                                         LZ-227      3          60.8       44.7                                        ______________________________________                                         *The lower the value for k.sub.a the lower the activity.                 

                  TABLE 23                                                        ______________________________________                                                               Consumption                                            Product   Example      of n-Butane                                                                              k.sub.a *                                   ______________________________________                                        NH.sub.4,L                                                                              --           26.0       5.0                                         LZ-228    6            12.9       4.8                                         LZ-229    5            6.5        4.2                                         ______________________________________                                         *The lower the value for k.sub.a the lower the activity.                 

EXAMPLE 12

(1) Five grams of an ammonium-exchanged ZSM-5 zeolite containing 5.10millimoles of aluminum, as Al₂ O₃, were slurried in 100 ml distilled H₂O. Because of the limited solubility of (NH₄)₂ TiF₆, the salt was addedto the slurry as crystals. The weight of added (NH₄)₂ TiF₆ was 1.00 gmand was an amount sufficient to replace 100% of the aluminum of thezeolite with titanium. The ZSM-5 zeolite and (NH₄)₂ TiF₆ slurry wererefluxed for 52 hours, filtered and washed with warm distilled wateruntil qualitative tests of the wash water were negative for bothaluminum and fluoride ions. The chemical analyses for the starting NH₄-ZSM-5 and the molecular sieve product (referred to herein as LZ-241)are set forth in Table 24.

                  TABLE 24                                                        ______________________________________                                                        Starting LZ-241                                                               NH.sub.4 -ZSM-5                                                                        Product                                              ______________________________________                                        Na.sub.2 O, weight percent                                                                      0.08       N.D.*                                            (NH.sub.4).sub.2 O, weight percent                                                              1.95       1.18                                             TiO.sub.2, weight percent                                                                       --         8.88                                             Al.sub.2 O.sub.3, weight percent                                                                5.09       2.60                                             SiO.sub.2, weight percent                                                                       93.07      88.34                                            F.sub.2, weight percent                                                                         0          <0.1                                             Na.sup.+ /Al:     0.03       0.0                                              NH.sub.4.sup.+ /Al:                                                                             0.75       0.89                                             K.sup.+ /Al:      0.78       0.89                                             Cation Equivalent,                                                                              0.78       0.89                                             M.sup.+ /Al:                                                                  SiO.sub.2 /Al.sub.2 O.sub.3 :                                                                   31.04      57.65                                            Si/(Al.sub.2 + Ti.sub.2):                                                                       --         18.15                                            ______________________________________                                         *None detected                                                           

A comparison of the properties of the LZ-241 product with the startingNH₄ ⁺ -ZSM-5 is shown in Table 25:

                  TABLE 25                                                        ______________________________________                                                       Starting LZ-241                                                               NH.sub.4 -ZSM-5                                                                        Product                                               ______________________________________                                        X-Ray Crystallinity:                                                          % by Peak Intensity                                                                            100        80                                                % by Peak Area:  100        72                                                Framework Infrared:                                                           Assymmetric Stretch,                                                                           1098       1103                                              cm.sup.-1 :                                                                   Symmetric Stretch,                                                                             794        797                                               cm.sup.-1 :                                                                   Hydroxyl Infrared:                                                            Absolute Absorbance                                                                            0.195      0.145                                             3710 cm.sup.-1                                                                Defect Structure 0.082      0.062                                             Factor, z:                                                                    ______________________________________                                    

(2) The novel zeolites denominated LZ-241 have the characteristiccrystal structure of zeolite ZSM-5 as indicated by an X-ray diffractionpattern having at least the d-spacings set forth in Table M below andhaving extraneous titanium atoms in the crystal lattice in the form ofTiO₄ tetrahedra, preferably in an amount of at least 1.0 per 10,000 Å³.

                  TABLE M                                                         ______________________________________                                        d(Å)     Relative Intensity                                               ______________________________________                                        11.1 ± 0.2                                                                              vs                                                               10.0 ± 0.2                                                                              s                                                                 6.3 ± 0.1                                                                              w                                                                 6.0 ± 0.1                                                                              w                                                                5.56 ± 0.1                                                                              mw                                                               5.01 ± 0.1                                                                              w                                                                4.60 ± 0.1                                                                              w                                                                4.25 ± 0.1                                                                              w                                                                3.85 ± 0.1                                                                              s                                                                3.71 ± 0.1                                                                              m                                                                3.04 ± 0.1                                                                              m                                                                2.99 ± 0.1                                                                              mw                                                               ______________________________________                                    

(3) To demonstrate that the titanium in the LZ-241 product is associatedwith the ZSM-5 crystals, Scanning Electron Micrographs (SEM) for thestarting ZSM-5 and the LZ-241 product were obtained. EDAX analysis ofthe crystals clearly shows that titanium is located in the crystals ofthe LZ-241 product. The properties of LZ-241 are consistent with theconclusion that the 8.88 weight percent TiO₂ found in the LZ-241 productrepresents titanium incorporated into the framework of the ZSM-5zeolite.

EXAMPLE 13

This is a comparative example wherein Example 1 of European PatentApplication No. 82109451.3 was repeated and the product evaluated byseveral techniques as hereinafter discussed:

(a) Example 1 of European Patent Application No. 82109451.3 was repeatedwith the starting reaction mixture having a composition based on molarratios of:

    1 Al.sub.2 O.sub.3 :47 SiO.sub.2 :1.32 TiO.sub.2 :11.7 NaOH:28 TPAOH:1498 H.sub.2 O

The reaction mixture was divided and placed in two digestion vessels. Atthe end of the procedure set forth in Example 1 of the Europeanapplication a sample of the product from each digestion vessel wasanalyzed and gave the following chemical analyses:

    ______________________________________                                                     Weight Percent                                                                Sample 1                                                                             Sample 2                                                  ______________________________________                                        SiO.sub.2      75.3     75.9                                                  Al.sub.2 O.sub.3                                                                             3.02     2.58                                                  TiO.sub.2      3.91     4.16                                                  Na.sub.2 O     3.66     3.46                                                  Carbon         6.3      6.7                                                   Nitrogen       0.62     0.65                                                  LOI*           14.0     14.0                                                  ______________________________________                                         *Loss on Ignition                                                        

The two samples were then analyzed by SEM (scanning electron microscope)and EDAX (energy dispersive analysis by X-ray) microprobe. The SEM probeof the two samples showed four morphologies to be present. The fourmorphologies of the two samples prepared in accordance with the Europeanapplication and the EDAX microprobe analysis for each morphology was asfollows:

(1) Smooth, intergrown hexagonal particles which are associated with aZSM-5 morphology had an EDAX microprobe of:

    ______________________________________                                                Average of Spot Probes                                                ______________________________________                                        Ti        0                                                                   Si        1.0                                                                 Al        0.05                                                                ______________________________________                                    

(2) Flat, smooth plates had an EDAX microprobe of:

    ______________________________________                                                Average of Spot Probes                                                ______________________________________                                        Ti        0.13                                                                Si        1.0                                                                 Al        0.05                                                                ______________________________________                                    

(3) Sphere and elongated bundles had an EDAX microprobe of:

    ______________________________________                                                Average of Spot Probes                                                ______________________________________                                        Ti        0.22                                                                Si        1.0                                                                 Al        0.05                                                                Na        0.10                                                                ______________________________________                                    

(4) Needles or fine rods had an EDAX microprobe of:

    ______________________________________                                                Average of Spot Probes                                                ______________________________________                                        Ti        0.05                                                                Si        0.8                                                                 Al        0.13                                                                Na        0.05                                                                Cl        0.10                                                                ______________________________________                                    

The above SEM and EDAX data demonstrate that although ZSM-5 typecrystals were formed that these crystals contained no detectabletitanium. The only detectable titanium was present as impurity phasesand was not present in a crystal having the ZSM-5 structure.

The X-ray diffraction patterns of the as-synthesized materials wereobtained and the following X-ray patterns were observed.

                  TABLE 26                                                        ______________________________________                                        (Sample 1)                                                                           2Θ                                                                            d(Å)                                                         ______________________________________                                                5.577                                                                              15.8467                                                                  5.950                                                                              14.8540                                                                  6.041                                                                              14.6293                                                                  6.535                                                                              13.5251                                                                  7.154                                                                              12.3567                                                                  7.895                                                                              11.1978                                                                  8.798                                                                              10.0504                                                                  9.028                                                                              9.7946                                                                   9.784                                                                              9.0401                                                                  11.846                                                                              7.4708                                                                  12.453                                                                              7.1079                                                                  12.725                                                                              6.9565                                                                  13.161                                                                              6.7267                                                                  13.875                                                                              6.3821                                                                  14.637                                                                              6.0518                                                                  14.710                                                                              6.0219                                                                  15.461                                                                              5.7310                                                                  15.881                                                                              5.5802                                                                  16.471                                                                              5.3818                                                                  17.218                                                                              5.1498                                                                  17.695                                                                              5.0120                                                                  19.212                                                                              4.6198                                                                  19.898                                                                              4.4619                                                                  20.045                                                                              4.4295                                                                  20.288                                                                              4.3770                                                                  20.806                                                                              4.2692                                                                  21.681                                                                              4.0988                                                                  22.143                                                                              4.0145                                                                  23.091                                                                              3.8516                                                                  23.641                                                                              3.7632                                                                  23.879                                                                              3.7263                                                                  24.346                                                                              3.6559                                                                  24.649                                                                              3.6116                                                                  25.548                                                                              3.4865                                                                  25.828                                                                              3.4494                                                                  26.228                                                                              3.3976                                                                  26.608                                                                              3.3501                                                                  26.887                                                                              3.3158                                                                  27.442                                                                              3.2524                                                                  28.048                                                                              3.1812                                                                  28.356                                                                              3.1473                                                                  29.191                                                                              3.0592                                                                  29.912                                                                              2.9870                                                                  30.295                                                                              2.9502                                                                  32.736                                                                              2.7356                                                                  33.362                                                                              2.6857                                                                  34.355                                                                              2.6102                                                                  34.640                                                                              2.5894                                                                  34.887                                                                              2.5716                                                                  35.152                                                                              2.5529                                                                  35.551                                                                              2.5252                                                                  35.660                                                                              2.5177                                                                  36.031                                                                              2.4926                                                                  37.193                                                                              2.4174                                                                  37.493                                                                              2.3987                                                                  45.066                                                                              2.0116                                                                  45.378                                                                              1.9985                                                                  46.514                                                                              1.9523                                                                  47.393                                                                              1.9182                                                           ______________________________________                                    

                  TABLE 27                                                        ______________________________________                                        (Sample 2)                                                                           2Θ                                                                            d(Å)                                                         ______________________________________                                                5.801                                                                              15.2353                                                                  6.012                                                                              14.7012                                                                  6.169                                                                              14.3265                                                                  7.970                                                                              11.0926                                                                  8.875                                                                              9.9636                                                                   9.118                                                                              9.6981                                                                   9.879                                                                              8.9532                                                                  11.933                                                                              7.4163                                                                  12.537                                                                              7.0605                                                                  12.808                                                                              6.9115                                                                  13.242                                                                              6.6860                                                                  13.957                                                                              6.3452                                                                  14.718                                                                              6.0186                                                                  14.810                                                                              5.9813                                                                  15.542                                                                              5.7014                                                                  15.954                                                                              5.5551                                                                  16.563                                                                              5.3521                                                                  17.316                                                                              5.1211                                                                  17.788                                                                              4.9862                                                                  19.291                                                                              4.6009                                                                  20.119                                                                              4.4134                                                                  20.382                                                                              4.3571                                                                  20.879                                                                              4.2544                                                                  21.735                                                                              4.0887                                                                  22.220                                                                              4.0007                                                                  23.170                                                                              3.8387                                                                  23.730                                                                              3.7494                                                                  23.964                                                                              3.7133                                                                  24.425                                                                              3.6442                                                                  24.722                                                                              3.6011                                                                  25.900                                                                              3.4399                                                                  26.734                                                                              3.3345                                                                  26.979                                                                              3.3047                                                                  27.251                                                                              3.2724                                                                  27.494                                                                              3.2440                                                                  28.175                                                                              3.1671                                                                  28.450                                                                              3.1371                                                                  29.287                                                                              3.0493                                                                  29.970                                                                              2.9814                                                                  30.371                                                                              2.9430                                                                  30.694                                                                              2.9127                                                                  31.312                                                                              2.8566                                                                  32.825                                                                              2.7283                                                                  33.457                                                                              2.6782                                                                  34.426                                                                              2.6051                                                                  34.723                                                                              2.5834                                                                  34.879                                                                              2.5722                                                                  35.709                                                                              2.5143                                                                  36.125                                                                              2.4863                                                                  37.248                                                                              2.4139                                                                  37.490                                                                              2.3988                                                                  45.156                                                                              2.0078                                                                  45.453                                                                              1.9954                                                                  46.462                                                                              1.9544                                                                  46.608                                                                              1.9486                                                           ______________________________________                                    

Tables 26 and 27 show an X-ray pattern typical of a ZSM-5 type productand can be attributed to the smooth, intergrown hexagonal particleswhich contained no titanium. The X-ray patterns of Tables 26 and 27 showthree peaks (2Θ=5.6-5.8, 12.45-12.54 and 24.5-24.72) which could not beexplained. Two samples were calcined with a separate portion of eachsample being calcined in air 540° C. for sixteen hours. Thesecalcination conditions correspond to those employed in EuropeanApplication No. 82109451.3. The X-ray patterns of the calcined productswere as follows:

                  TABLE 28                                                        ______________________________________                                        (Sample 1)                                                                           2Θ                                                                            d(Å)                                                         ______________________________________                                                6.141                                                                              14.3908                                                                  6.255                                                                              14.1303                                                                  8.011                                                                              11.0355                                                                  8.913                                                                              9.9209                                                                   9.144                                                                              9.6705                                                                   9.930                                                                              8.9068                                                                  11.979                                                                              7.3876                                                                  12.440                                                                              7.1152                                                                  13.289                                                                              6.6625                                                                  14.007                                                                              6.3224                                                                  14.874                                                                              5.9557                                                                  15.613                                                                              5.6757                                                                  15.995                                                                              5.5408                                                                  16.609                                                                              5.3373                                                                  17.353                                                                              5.1103                                                                  17.884                                                                              4.9597                                                                  19.335                                                                              4.5905                                                                  20.177                                                                              4.4008                                                                  20.463                                                                              4.3401                                                                  20.940                                                                              4.2422                                                                  21.845                                                                              4.0685                                                                  22.291                                                                              3.9880                                                                  23.186                                                                              3.8361                                                                  23.362                                                                              3.8076                                                                  23.817                                                                              3.7359                                                                  24.031                                                                              3.7031                                                                  24.510                                                                              3.6317                                                                  24.908                                                                              3.5747                                                                  25.699                                                                              3.4664                                                                  25.969                                                                              3.4309                                                                  26.371                                                                              3.3796                                                                  26.698                                                                              3.3389                                                                  27.022                                                                              3.2996                                                                  27.487                                                                              3.2449                                                                  28.184                                                                              3.1662                                                                  28.513                                                                              3.1303                                                                  29.369                                                                              3.0411                                                                  30.017                                                                              2.9769                                                                  30.468                                                                              2.9338                                                                  31.333                                                                              2.8548                                                                  32.877                                                                              2.7241                                                                  34.490                                                                              2.6003                                                                  35.062                                                                              2.5592                                                                  35.800                                                                              2.5082                                                                  36.186                                                                              2.4823                                                                  37.324                                                                              2.4092                                                                  37.654                                                                              2.3888                                                                  45.195                                                                              2.0062                                                                  45.631                                                                              1.9880                                                                  46.639                                                                              1.9474                                                                  47.547                                                                              1.9123                                                                  48.765                                                                              1.8674                                                           ______________________________________                                    

                  TABLE 29                                                        ______________________________________                                        (Sample 2)                                                                           2Θ                                                                            d(Å)                                                         ______________________________________                                                6.092                                                                              14.5084                                                                  6.295                                                                              14.0403                                                                  7.941                                                                              11.1328                                                                  8.838                                                                              10.0054                                                                  9.857                                                                              8.9730                                                                  11.921                                                                              7.4236                                                                  12.399                                                                              7.1383                                                                  13.222                                                                              6.6959                                                                  13.937                                                                              6.3539                                                                  14.811                                                                              5.9809                                                                  15.535                                                                              5.7038                                                                  15.916                                                                              5.5681                                                                  16.532                                                                              5.3620                                                                  17.262                                                                              5.1370                                                                  17.806                                                                              4.9811                                                                  19.268                                                                              4.6064                                                                  20.107                                                                              4.4160                                                                  20.389                                                                              4.3556                                                                  20.868                                                                              4.2567                                                                  21.807                                                                              4.0754                                                                  22.197                                                                              4.0047                                                                  23.116                                                                              3.8476                                                                  23.263                                                                              3.8235                                                                  23.755                                                                              3.7455                                                                  23.955                                                                              3.7147                                                                  24.432                                                                              3.6433                                                                  24.854                                                                              3.5823                                                                  25.653                                                                              3.4725                                                                  25.901                                                                              3.4398                                                                  26.265                                                                              3.3929                                                                  26.648                                                                              3.3451                                                                  26.976                                                                              3.3052                                                                  27.386                                                                              3.2566                                                                  28.156                                                                              3.1692                                                                  28.495                                                                              3.1323                                                                  29.304                                                                              3.0476                                                                  29.969                                                                              2.9815                                                                  30.384                                                                              2.9417                                                                  31.283                                                                              2.8592                                                                  32.819                                                                              2.7289                                                                  34.423                                                                              2.6052                                                                  34.993                                                                              2.5641                                                                  35.716                                                                              2.5138                                                                  36.146                                                                              2.4850                                                                  37.295                                                                              2.4110                                                                  37.562                                                                              2.3944                                                                  45.137                                                                              2.0086                                                                  45.523                                                                              1.9925                                                                  46.562                                                                              1.9504                                                                  47.509                                                                              1.9137                                                           ______________________________________                                    

The X-ray diffraction patterns of the calcined samples show a ZSM-5 typepattern with only slight differences from the as-synthesized. Whenchemical analysis (bulk) of a portion of the calcined samples 1 and 2was carried out the following was obtained:

    ______________________________________                                                     Weight Percent                                                                Sample 1                                                                             Sample 2                                                  ______________________________________                                        SiO.sub.2      79.6     81.2                                                  Al.sub.2 O.sub.3                                                                             3.5      2.9                                                   Na.sub.2 O     4.4      4.1                                                   TiO.sub.2      4.4      4.6                                                   C              0.1      0.10                                                  LOI            8.1      7.6                                                   ______________________________________                                    

When the molar ratio of oxides is computed for the above bulk analysisthe following is obtained:

    1 SiO.sub.2 :0.043 TiO.sub.2 :0.021 Al.sub.2 O.sub.3 :0.049 Na.sub.2 O

This compares quite well with the bulk chemical analysis reported in theEuropean application which is:

    1 SiO.sub.2 : 0.047 TiO.sub.2 :0.023 Al.sub.2 O.sub.3 :0.051 Na.sub.2 O

Although it is clear that the product crystals which gave the product anX-ray pattern characteristic of ZSM-5 contained no titanium, the bulkanalysis of the product showed titanium to be present as a result ofimpurity crystal not having an X-ray pattern characteristic of ZSM-5.

EXAMPLE 14

This is a comparative example in which Example 8 of U.S. Pat. No.4,410,501 was repeated and the product analyzed by several techniques.

A 2 liter beaker was placed on a stirring hotplate to which there wereadded 414.5 mL of distilled water. Titanium ethoxide, 26.55 gm, wasadded to the distilled H₂ O while stirring. A white gelatinousprecipitate/suspension formed. The above suspension was cooled in an icebath to 5° C. at which time 318.6 mL of a separately cooled 30% solutionof H₂ O₂ was added at a moderate rate. The slurry turned orange with thesuspension/precipitate still present. The temperature was maintained at5° C. for two hours with occasional stirring. The precipitate graduallydissolved and the solution became clear orange. A pre-cooled (5° C.)solution of 22.4% TPA-OH was added with moderate stirring and at amoderate rate to the titanium containing solution. The solution changedfrom orange to yellow. The solution was stirred at 5° C. for 1 hour,with the solution effervescing the entire time.

Separately, 1.042 gm NaAlO₂ were added to 84.89 gm Ludox-AS40 withstirring. The aluminate dissolved slowly. The NaAlO₂ /Ludox solution wasadded to the yellow titanium containing solution. The entire mix becametranslucent yellow. The mixture was covered with a watch glass, removedfrom the ice bath and allowed to stand at room temperature overnight.Effervescence continued, even until the next morning. The coveredsolution was heated to 75° C. At about 65°, the solution became cloudyand thickened, but as the temperature increased, the solution becameclearer. The solution was heated at 75° C. for 7 hours, then loaded intoa 2 liter reactor and heated to 175° C. for 10 days. On cooling, thecrystals were separated from the liquid phase and the crystals werewashed thoroughly with hot distilled water. This sample was identifiedas sample TA.

The X-ray powder pattern of sample TA was obtained and wascharacteristic of a well crystallized MFI type zeolite, i.e., ZSM-5 orsilicalite. The pattern also showed several additional peaks at 25.3°,47.9° and 54.9° 2Θ which are indicative of crystalline TiO₂, anatasephase.

The chemical analysis of sample TA is shown in the following Table:

    ______________________________________                                        (TPA).sub.2 O, wt. %:                                                                             9.13                                                      SiO.sub.2, wt. %:   79.70                                                     Al.sub.2 O.sub.3, wt. %:                                                                          1.30                                                      TiO.sub.2, wt. %:   6.03                                                      SiO.sub.2 /Al.sub.2 O.sub.3 :                                                                     103.73                                                    Cation Equivalent, M+/Al:                                                                         1.60                                                      ______________________________________                                    

The data show the incorporation of a substantial amount of TiO₂ into theproduct composition with a small amount of Al₂ O₃ as well.

The infrared spectrum of sample TA was also obtained and showedabsorption bands at about 620 cm⁻¹, 760 cm⁻¹ and 985 cm⁻¹. In the abovereferenced patent, U.S. Pat. No. 4,410,501, Taramasso reports a band atabout 950 cm⁻¹ which he attributes to Ti⁺⁴ in tetrahedral coordinationwith Si⁺⁴. In Taramasso's subsequent publication with Perego et al.,"Titanium-Silicalite: A Novel Derivative in the Pentasil Family", in"New Developments in Zeolite Science and Technology", Proceedings of the7th International Zeolite Conference, Tokyo, Aug. 17-22, 1986, Murakamiet al. eds., pp. 129-136, he states on pg. 132, that the infraredabsorption band is located at 970 cm⁻¹. Inspection of the spectrapresented in the '501 patent does indeed suggest that the band islocated at about 970 cm⁻¹, and not at the lower frequency as suggestedby Taramasso in column 2, lines 38- 41 of the '501 patent.

In a recent report by Kornatowski et al., "Growth of Large Crystals ofTitanium Molecular Sieve of ZSM-5 Structure, Presented at the 8thInternational Zeolite Conference, Amsterdam, Jul. 10-14, 1989, the 970cm⁻¹ band assignment is attributed to extra framework TiO₂ species,"contrary to Taramasso". Both the Taramasso and the Perego referencesrely on the report of Best and Condrate, "A Raman study of TiO₂ -SiO₂Glasses Prepared by Sol-Gel Processes", J. Mat. Sci. Leters 4 (1985),994-98 which reports on the Raman spectra of TiO₂ -SiO₂ glasses. Theysuggest a band at about 950 cm⁻¹ which they attribute to tetrahedrallycoordinated titanium in glasses containing very small quantities oftitanium. The Best et al. paper, supports the premise that the 620 cm⁻¹and 760 cm⁻¹ bands at least are due to the presence of anatase TiO₂ andthat the 985 cm⁻¹ band is indeed, extra framework TiO₂ in transitionfrom the glass phase to anatase, and not to titanium in tetrahedralcoordination with silicon. Thus, none of the infrared bands observed forthe TA sample is attributable to tetrahedrally coordinated titanium.

SEM and EDAX examination of sample TA showed crystals of severalmorphologies. The bulk of the crystals were spherulitic aggregates oragglomerates, with some rod shaped crystals present. The rod shapedmorphology could be attributable to a silicalite type phase-no aluminumin the MFI framework, while the spherulitic aggregates are typical ofthe ZSM-5 morphology-MFI framework containing aluminum. There was somedebris observed with no regular morphology. In addition, the crystalsappeared to have debris covering their surfaces as well. EDAX showed thepresence of a small amount of titanium throughout the entire sample.There were however, substantially higher levels of Ti in areas heavy indebris. Since the spot probe of the EDAX covers areas substantiallygreater than the crystal sizes under observation, AnalyticalTransmission Electron Microscopy was used to analyze smaller areas ofthe crystals. The ATEM measures an area of 200 square Angstroms, ratherthan the approximately four square micron areas measured by the spotprobe of the SEM.

ATEM examination was performed on the product by two methods. The first,the "dry brush" method looks only at the outside surfaces of thematerial under observation. The other method uses a microtome method toprepare thin slices of the material, thus allowing the observation andanalysis of the interior portions of the material. In the dry brushmethod, both crystal morphologies were examined, as was the debris. Spotprobe analysis of the debris showed that this particle is TiO₂. Spotprobe analysis of the rod-like crystals (morphology of silicalite)showed a small amount of titanium and nearly no aluminum. The rods havea surface coating of debris. Crystals with a ZSM-5 type morphology werealso analyzed. Aluminum is present in these crystals, but the level oftitanium is very low. Again these crystals were covered with debris.Microtome analysis of thin sections of the crystals gave the sameresults as the dry brush method. That is, the silicalite rod-likecrystal showed very little titanium and no aluminum while the ZSM-5 typecrystals show the presence of aluminum, but the titanium is barelydetectable.

The SEM and EDAX data show that the titanium introduced into thesynthesis gel, precipitated, as the aqueous chemistry at this high pHwould predict, and crystallized as the anatase phase of TiO₂, depositingon the filter cake with the zeolite crystals and coating the crystalswith some of the tinier, non-agglomerated TiO₂ phases.

The data obtained from the extensive analysis of sample TA shows thatthere is no valid reason to conclude that Ti, present in the bulkanalysis of the solid, is present in the framework of the zeolite. Thematerial contains greater than 6 wt .% TiO₂ ; most of it can beaccounted for by the presence of anatase in the X-ray powder pattern.Another small fraction can be observed coating the surface of thezeolite crystals. These small particles are too small to be observed inthe X-ray powder pattern. The Analytical TEM show consistently, that theoutside surface of the crystals ("dry brush" samples) contain more Tithan the interior portions of the crystal (microtome sections). The factthat a barely detectable amount of Ti is found inside the crystals canbe accounted for by several reasons, without invoking substitution inthe framework. The Ti could very well be left on the surface of thecrystal by the very technique that allows us to observe the interiorportions of the crystal, the microtome technique. A more likely sourceis the presence of Ti in the template, which is inside the zeolite poresas a structure directing "template" during the synthesis.

EXAMPLE 15

A gel containing 1799.3 gm Al₂ (SO₄)₃ dissolved in a solution of 656.5gm NaOH in 3,947.3 gm H₂ O is prepared in a 12 liter round bottomedflask and stirred. 4,689.8 gm of Na-silicate is added gradually to thealumina gel. Heat was applied to the flask and 554.6 gm of zeolite omegaseed is added to the system. The mixed gel was refluxed for 115 hours,filtered, washed and dried at room temperature. X-ray powder diffractionanalysis of the product showed that the sample (designated LZ-202-II) isLZ-202 of excellent quality.

About 250 gm of the LZ-202 prepared above are exchanged three times atreflux with a solution containing 250 gm of ammonium chloride in water.Following ion-exchange, the product is washed with hot deionized waterand dried at room temperature, and is designated LZ-202-II-NH₄.

a) Two gm (anhydrous weight) of the ammonium-exchanged LZ-202-II-NH₄ areplaced in a beaker containing 50 ml of distilled water and heated to 95°C. with stirring. A second solution containing 0.7262 gm of ammoniumfluorotitanate in 50 ml distilled water is prepared and added to thezeolite slurry in 2 ml increments. This amount is sufficient to reactwith and replace 50 atomic percent of the aluminum in the zeoliteframework. Two minutes equilibration time is allowed between eachaddition step. Following addition of the fluorotitanate solution, thetemperature of the reaction mixture is maintained at 95° C. and themixture digested for one hour. Following digestion, the sample isfiltered and washed free of fluoride. The physical and chemicalproperties of the product which is designated LZ-247-a, are compared tothe starting LZ-202-II and the ammonium-exchanged product, LZ-202-II-NH₄in Table 1.

The following relationships are calculated from a determination of themole fractions of oxides:

    ______________________________________                                        a)    Mole fraction of aluminum removed; N:                                                                 0.073                                           b)    Percent dealumination; N/a × 100:                                                               33                                              c)    Change in Defect Structure Factor; z:                                                                 0.050                                           d)    Moles of Ti substituted per mole of                                                                   >1                                                    Al removed from the zeolite:                                            ______________________________________                                    

EXAMPLE 16

A sample is prepared as described in Example 1, except that followingaddition of the fluorotitanate the reaction mixture is refluxed for 6hours. The chemical and physical properties of this sample are listedunder LZ-247-b in Table 1.

From calculated mole fractions the following relationships are derived:

    ______________________________________                                        a)    Mole fraction of aluminum removed; N:                                                                 0.095                                           b)    Percent dealumination; N/a × 100:                                                               43                                              c)    Change in Defect Structure Factor; z:                                                                 0.058                                           d)    Moles of Ti substituted per mole of                                                                   >1                                                    Al removed from the zeolite:                                            ______________________________________                                    

These Examples show that as a result of the treatment of the ammoniumexchanged LZ-202 with ammonium fluorotitanate, aluminum is removed fromthe zeolite framework and titanium remains in the zeolite. Thecharacterization data show that the bulk of the titanium is insertedinto the LZ-202 framework in place of the aluminum. The X-ray powderpattern does not contain any extraneous peaks nor does it show anyincreased background that would be indicative of an amorphous deposit,yet the samples contain 11-16 weight percent TiO₂. The treated zeoliteproducts are 33-43 percent depleted in Al but the absorbance in thehydroxyl region of the infrared spectra, indicative of dealumination, isrelatively insignificant. The asymmetric stretch band in the frameworkinfrared spectrum is shifted to higher wavenumbers commensurate with thedealumination. The symmetric stretch band, which shifts to higherwavenumbers when the smaller Si atom replaces Al in the framework, inthis case has shifted to smaller wavenumbers, perhaps due tosubstitution of the larger Ti atom in the framework. All of theproperties of the LZ-247 products taken together indicate that titaniumhas replaced aluminum in the framework of the LZ-202.

The above Examples do not represent optimized treatment conditions, butserve merely to demonstrate that Zeolite LZ-202 will withstand thetreatment conditions without serious degradation and that Ti willsubstitute for Al in the zeolite framework of LZ-202.

                  TABLE 30                                                        ______________________________________                                                                   EXAM-    EXAM-                                                LZ-202-                                                                              LZ-202-  PLE 15   PLE 16                                               II     II-NH.sub.4                                                                            LZ-247-a LZ-247-b                                  ______________________________________                                        (NH.sub.4).sub.2 O, wt %                                                                   --       8.79     5.77   5.10                                    Na.sub.2 O, wt %                                                                           10.60    <0.02    0.00   0.00                                    Al.sub.2 O.sub.3, wt %                                                                     18.26    18.70    13.05  11.24                                   TiO.sub.2, wt %                                                                            0.00     0.00     11.89  14.02                                   SiO.sub.2, wt %                                                                            70.20    72.98    69.63  70.22                                   F.sub.2 wt % --       --       0.39   0.63                                    SiO.sub.2 /Al.sub.2 O.sub.3                                                                6.52     6.62     9.05   10.60                                   SiO.sub.2 /(Al.sub.2 O.sub.3 +                                                             6.52     6.62     5.72   5.90                                    TIO.sub.2 /2)                                                                 Cation Equivalent,                                                                         0.95     0.92     0.87   0.89                                    M+/Al                                                                         X-ray Crystallinity:                                                          % by Intensity                                                                             100      117      64     48                                      % by Area    100      120      64     48                                      Framework Infrared                                                            Asymmetric Stretch,                                                                        1036     1038     1048   1051                                    cm.sup.-1                                                                     Symmetric Stretch,                                                                         817      815      814    813                                     cm.sup.-1                                                                     Hydroxyl Infrared                                                             Absorbance   0.107    0.114    0.230  0.250                                   @ 3710 cm.sup.-1                                                              Defect Structure                                                                           0.045    0.048    0.098  0.106                                   Adsorption Capacity:                                                          wt. % O.sub.2 @ 100 torr,                                                                  17.28    18.18    16.39  16.50                                   and 90K                                                                       wt % H.sub.2 O @ 4.6 torr,                                                                 17.76    18.48    15.78  14.68                                   and 239° K.                                                            ______________________________________                                    

PROCESS APPLICATIONS

The molecular sieve compositions of this invention have unique surfacecharacteristics making them useful as molecular sieves and as catalystor as bases for catalysts in a variety of separation, hydrocarbonconversion and oxidative combustion processes. These compositions can beimpregnated or otherwise associated with catalytically active metals bythe numerous methods known in the art and used, for example, infabricating catalyst compositions containing alumina or aluminosilicatematerials.

One use of the crystalline materials of this invention is to separatemixtures of molecular species. Prior to use in a separation process, theTASO-45 materials are activated to remove at least some of any molecularspecies, e.g., templating agent, which may be present in theintracrystalline pore system as a result of synthesis. This may beaccomplished as described above, i.e., by heating.

The crystalline materials of this invention are capable of separatingmixtures of molecular species based on the molecular size (kineticdiameters) or on the degree of polarity of the molecular species. Whenthe separation of molecular species is based on molecular size, thecrystalline microporous material is chosen in view of the dimensions ofits pores such that at least the smallest molecular specie of themixture can enter the intracrystalline void space while at least thelargest specie is excluded. The kinetic diameters of various moleculessuch as oxygen, nitrogen, carbon dioxide, carbon monoxide are providedin D. W. Breck, ZEOLITE MOLECULAR SIEVES, John Wiley and Sons (1974) p.636.

When the separation is based on degree of polarity, it is generally thecase that the more hydrophilic TASO-45 material of this invention willpreferentialy adsorb the more polar molecular species of a mixturehaving different degrees of polarity even though both molecular speciescan communicate with the pore system of the crystalline material. Forexample water, which is more polar, will be preferentially adsorbed overcommon hydrocarbon molecules such as paraffins, olefins, etc. Thus, theTASO-45 materials of this invention can be used as dessicants in suchadsorption separation/purification processes as natural gas drying,cracked gas drying, etc.

If one of the molecular species, e.g., water, is a small impurity, theseparation may be effected in the conventional manner by simply passingthe stream to be treated through a bed of the particular crystallinematerial desired. As the operation of the process continues, theredevelops in the bed a so-called "front" between the material loaded withthe impurity, e.g., water, and the material not so loaded. This frontmoves through the bed in the direction of gas flow. Before the frontreaches the downstream end of the bed, the bed is regenerated by cuttingoff the flow of feed stream and passing through the bed a purge gaswhich (usually at a temperature of about 50°-150° C.) desorbs theimpurity, e.g., water, from the bed. If the purge gas is adsorbed on thebed, this gas can be removed by passing one or two bed volumes of thefeed stream through the bed.

If the concentration of one of the species in the mixture is large,e.g., several percents, other conventional techniques, such as pressureswing adsorption (PSA) and thermal swing adsorption may be used. Suchtechniques are well known to those skilled in the separation art. See,e.g., U.S. Pat. Nos. 4,723,966, 4,589,888, and 4,398,926. For example, apressure swing adsorption process will operate at a temperature andpressure sufficient to effect the adsorption and desorption of thecomponent or molecular specie which one wants to remove. Typically thetemperature is preferably maintained in the range of about -50° to 100°C. and preferably from about 0° to 50° C. The pressure during adsorptioncan vary from about 0.2 psia (1.4 kPa) to about 1500 psia (10,342 kPa),preferably from about 50 psia (344 kPa) to about 500 psia (3,447 kPa)and more preferably from about 75 psia (517 kPa) to about 350 psia(2,413 kPa). The pressure during desorption is lower than duringadsorption and effective to cause desorption of the adsorbed component.The range of this pressure is from about 0.1 torr (1.3 Pa) to 150 psia(1,034 kPa), preferably from about 0.1 torr (1.3 Pa) to 15 psia (103kPa) and more preferably from about 0.1 torr (1.3 Pa) to about 250 torr(333 Pa). The cyclic process can comprise additional adsorption andregeneration steps as well as intermediate depressurization and purgingsteps.

The hydrocarbon conversion reactions which may be catalyzed by theinstant molecular sieve compositions include: cracking, hydrocracking;alkylation of both the aromatic and isoparaffin types; isomerization(including xylene isomerization); polymerization; reforming;hydrogenation; dehydrogenation; transalkylation; dealkylation; andhydration.

When catalyst compositions containing the instant molecular sievecompositions also contain a hydrogenation promoter, such promoter may beplatinum, palladium, tungsten, nickel or molybdenum and may be used totreat various petroleum stocks including heavy petroleum residualstocks, cyclic stocks and other hydrocrackable charge stocks. Thesestocks can be hydrocracked at temperatures in the range of between about400° F. and about 825° F. using molar ratios of hydrogen to hydrocarbonin the range of between about 2 and about 80, pressures between about 10and about 3500 psig, and a liquid hourly space velocity (LHSV) ofbetween about 0.1 and about 20, preferably between about 1.0 and about10.

Catalyst compositions containing the instant molecular sievecompositions may also be employed in reforming processes in which thehydrocarbon feedstocks contact the catalyst at temperatures betweenabout 700° F. and about 1000° F., hydrogen pressures of between about100 and about 500 psig, LHSV values in the range between about 0.1 andabout 10 and hydrogen to hydrocarbon molar ratios in the range betweenabout 1 and about 20, preferably between about 4 and about 12.

Further, catalysts containing the instant molecular sieve compositionswhich also contain hydrogenation promoters, are also useful inhydroisomerization processes wherein the feedstock(s), such as normalparaffins, is converted to saturated branched-chain isomers.Hydroisomerization processes are typically carried out at a temperaturebetween about 200° F. and about 600° F., preferably between about 300°F. and about 550° F. with an LHSV value between about 0.2 and about 1.0.Hydrogen is typically supplied to the reactor in admixture with thehydrocarbon feedstock in molar proportions of hydrogen to the feedstockof between about 1 and about 5.

Catalyst compositions similar to those employed for hydrocracking andhydroisomerization may also be employed at between about 650° F. andabout 1000° F., preferably between about 850° F. and about 950° F. andusually at somewhat lower pressures within the range between about 15and about 50 psig for the hydroisomerization of normal paraffins.Preferably the paraffin feedstock comprises normal paraffins having acarbon number range of C₇ -C₂₀. The contact time between the feedstockand the TiSO containing catalyst is generally relatively short to avoidundesirable side reactions such as olefin polymerization and paraffincracking. LHSV values in the range between about 0.1 and about 10,preferably between about 1.0 and about 6.0, are suitable.

The low alkali metal content (often not measurable by current analyticaltechniques) of the instant compositions make them particularly wellsuited for use in the conversion of alkylaromatic compounds,particularly for use in the catalytic disproportionation of toluene,xylene, trimethylbenzenes, tetramethylbenzenes and the like. In suchdisproportionation processes it has been observed that isomerization andtransalkylation can also occur. The catalysts containing the instantmolecular sieve compositions and employed for such processes willtypically include Group VIII noble metal adjuvants alone or inconjunction with Group VI-B metals such as tungsten, molybdenum andchromium which are preferably included in such catalyst compositions inamounts between about 3 and about 15 weight % of the overall catalystcomposition. Extraneous hydrogen can, but need not, be present in thereaction zone which is maintained at a temperature between about 400°and about 750° F., pressures in the range between about 100 and about2000 psig and LHSV values in the range between about 0.1 and about 15.

Catalysts containing the instant molecular sieve compositions may beemployed in catalytic cracking processes wherein such are preferablyemployed with feedstocks such as gas oils, heavy naphthas, deasphaltedcrude oil residues, etc., with gasoline being the principal desiredproduct. Temperature conditions are typically between about 850° andabout 1100° F., LHSV values between about 0.5 and about 10, pressureconditions are between about 0 psig and about 50 psig.

Catalysts containing the instant molecular sieve compositions may beemployed for dehydrocyclization reactions which employ paraffinichydrocarbon feedstocks, preferably normal paraffins having more than 6carbon atoms, to form benzene, xylenes, toluene and the like.Dehydrocyclization processes are typically carried out using reactionconditions similar to those employed for catalytic cracking. For suchprocesses it is preferred to use a Group VIII non-noble metal cationsuch as cobalt and nickel in conjunction with the molecular sievecomposition.

Catalysts containing the instant molecular sieve compositions may beemployed in catalytic dealkylation where paraffinic side chains arecleaved from aromatic nuclei without substantially hydrogenating thering structure at relatively high temperatures in the range betweenabout 800° F. and about 1000° F. at moderate hydrogen pressures betweenabout 300 and about 1000 psig with other conditions being similar tothose described above for catalytic hydrocracking. Catalysts employedfor catalytic dealkylation are of the same type described above inconnection with catalytic dehydrocyclization. Particularly desirabledealkylation reactions contemplated herein include the conversion ofmethylnaphthalene to naphthalene and toluene and/or xylenes to benzene.

Catalysts containing the instant molecular sieve compositions may beused in catalytic hydrofining wherein the primary objective is toprovide for the selective hydrodecomposition of organic sulfur and/ornitrogen compounds without substantially affecting hydrocarbon moleculespresent therewith. For this purpose, it is preferred to employ the samegeneral conditions described above for catalytic hydrocracking. Thecatalysts are the same typically of the same general nature as describedin connection with dehydrocyclization operations. Feedstocks commonlyemployed for catalytic hydroforming include: gasoline fractions;kerosenes; jet fuel fractions; diesel fractions; light and heavy gasoils; deasphalted crude oil residua; and the like. The feedstock maycontain up to about 5 weight percent of sulfur and up to about 3 weightpercent of nitrogen.

Catalysts containing the instant molecular sieve compositions may beemployed for isomerization processes under conditions similar to thosedescribed above for reforming although isomerization processes tend torequire somewhat more acidic catalysts than those employed in reformingprocesses. Olefins are preferably isomerized at temperatures betweenabout 500° F. and about 900° F., while paraffins, naphthenes and alkylaromatics are isomerized at temperatures between about 700° F. and about1000° F. Particularly desirable isomerization reactions contemplatedherein include the conversion of n-heptane and/or n-octane toisoheptanes, isooctanes, butane to iso-butane, methylcyclopentane tocyclohexane, meta-xylene and/or ortho-xylene to para-xylene, 1-butene to2-butene and/or isobutene, n-hexene to isohexane, cyclohexane tomethylcyclopentene, etc. The preferred cation form is a combination of amolecular sieve of this invention and polyvalent metal compounds (suchas sulfides) of metals of Group II-A, Group II-B and rare earth metals.For alkylation and dealkylation processes the instant molecular sievecompositions having pores of at least 5 Å are preferred. When employedfor dealkylation of alkyl aromatics, the temperature is usually at least350° F. and ranges up to a temperature at which substantial cracking ofthe feedstock or conversion products occurs, generally up to about 700°F. The temperature is preferably at least 450° F. and not greater thanthe critical temperature of the compound undergoing dealkylation.Pressure conditions are applied to retain at least the aromatic feed inthe liquid state. For alkylation the temperature can be as low as 250°F., but is preferably at least 350° F. In alkylation of benzene, tolueneand xylene, the preferred akylation agents are olefins such as ethyleneand propylene.

The molecular sieve compositions of this invention may be employed inconventional molecular sieve processes as heretofore have been carriedout using aluminosilicate, aluminophosphate or other commonly employedmolecular sieves. The instant compositions are preferably activated,e.g., calcined in air or nitrogen, prior to their use in a molecularsieve process.

We claim as our invention:
 1. A process for separating a mixture ofmolecular species having different kinetic diameters comprising flowingthe mixture through a bed containing a molecular sieve composition,having an intracrystalline pore system, at a temperature of about -50°to 100° C. and a pressure from about 0.2 psia to about 1500 psia therebyadsorbing at least some molecules of the molecular species whose kineticdiameters are sufficiently small to enter into the intracrystalline poresystem of the molecular sieve composition, the molecular sievecomposition further characterized in that it has a three-dimensionalmicroporous framework structure of AlO₂, SiO₂ and TiO₂ tetrahedral oxideunits and has a unit empirical formula on an anhydrous basis of:

    (Ti.sub.w Al.sub.x Si.sub.y)O.sub.2

where w, x, and y represent the mole fractions of titanium, aluminum andsilicon respectively, present as framework tetrahedral oxide units, saidmole fractions being such that they are within the trigonal area definedby points A, B and C of FIG. 1, which points have the following valuesof w, x and y:

    ______________________________________                                               Mole Fraction                                                          Point    w              x      y                                              ______________________________________                                        A        0.49           0.01   0.50                                           B        0.01           0.49   0.50                                           C        0.01           0.01   0.98                                           ______________________________________                                    

the molecular sieve being at least partially activated.
 2. A process forseparating a mixture of molecular species having different degrees ofpolarity comprising flowing the mixture through a bed containing amolecular sieve composition, having an intracrystalline, pore system, ata temperature of about -50° to 100° C. and a pressure from about 0.2psia to about 1500 psia thereby adsorbing at least some of the morepolar molecules in said mixture into the intracrystalline pore system ofthe molecular sieve composition, the molecular sieve composition furthercharacterized in that it has a three-dimensional microporous frameworkstructure of AlO₂, SiO₂ and TiO₂ tetrahedral oxide units and having aunit empirical formula on an anhydrous basis of:

    (Ti.sub.w Al.sub.x Si.sub.y)O.sub.2

where w, x, and y represent the mole fractions of titanium, aluminum andsilicon respectively, present as framework tetrahedral oxide units, saidmole fractions being such that they are within the trigonal area definedby points A, B and C of FIG. 1, which points have the following valuesof w, x and y:

    ______________________________________                                               Mole Fraction                                                          Point    w              x      y                                              ______________________________________                                        A        0.49           0.01   0.50                                           B        0.01           0.49   0.50                                           C        0.01           0.01   0.98                                           ______________________________________                                    

the molecular sieve being at least partially activated in order toseparate said mixture.